Troubleshooting steps:
1. Make sure Outlook Express and POP3 are allowed in your firewall
2. Restart Outlook Express
3. Restart your computer
4. Disable email scanning in your anti-virus program
5. Call your ISP to see if there is a problem with their mail servers
6. Delete and recreate the email account in Outlook Express
7. Do a system restore to a point before the problem started
8. Try a different email program such as Mozilla Thunderbird
Error Number 0x80042108
Problem:
Your e-mail program gives you error number 0x80042108. The error box may say:
"Outlook is unable to connect to your incoming (POP3) e-mail server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP)"
Solution:
1) Restart your computer. Often the problem will then simply fix itself and everything will work again. In fact, the vast majority of the time when Visionary customers have called me with this error number, restarting the computer has fixed it. So, even if you already have restarted, do it again. Go into the Start menu and choose Restart (or if you don't have Restart, click Shutdown / Turn off Computer, then choose Restart).
2) If you recently updated Office or Outlook, that is probably the problem. The one time I've recorded where restarting didn't fix the problem with 0x80042108, this was what had happened. You may be able to undo the update using System Restore (for help doing that click here). Or try re-installing Office, or something along those lines.
2) If after restarting you still get the same error number, and step 2 does not apply or does not fix things, disable email scanning in Norton or McAfee or whatever anti-virus program you use (for help doing this in Norton, click here). Then close your email program, open it again, and try getting your mail.
3) Remove and then re-create your email account. To do this in Outlook Express, follow the steps here. For Microsoft Office Outlook click here.
4) Before doing this step, make sure you have your Norton/Symantec CD or product code so you can re-install it. Then, completely uninstall all Norton/Symantec software in the Add/Remove Programs control panel (see the Microsoft article here). Test it to see if your e-mail is working now. If it is, re-install the Norton/Symantec software. Turn off e-mail scanning. Try checking your e-mail again to make sure it's still working with the Norton/Symantec software installed again.
If none of that worked:
5) If the problem just recently started, I suppose you can simply do a system restore to try to undo whatever it was that happened. You can only do this if your version of Windows has System Restore. For instructions, click here.
6) One very rare cause of this: if you're on high speed internet, you may need to have a default gateway programmed in (to program it in, go to Control Panels > Network Connections > Right-click on Local Area Connection and choose Properties > Highlight Internet Protocol (TCP/IP) > Properties). You'll have to know what the gateway is supposed to be, otherwise your connection will stop working entirely. Again, this is a very rare cause for this error number, but I found a thread on a forum once indicating this as causing 0x80042108.
7) According to Microsoft this error number can also result from corrupted files on the hard drive. In this case, reinstalling your email program may solve the problem. Or, you could try switching to a different e-mail program such as Mozilla Thunderbird. You can download Thunderbird for free from http://www.mozilla.org. Hopefully the problem will not persist in Thunderbird.
Reference: http://www.vcn.com/knowledgebase/article.php?id=386
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Method 1: Start Outlook in safe mode
To start Outlook in safe mode:
Windows Vista
1. Click Start.
2. Type outlook.exe /safe in the Start Search box.
3. Press Enter.
Method 2: Create a new e-mail profile
You may be able to resolve these problems by creating a new e-mail profile.
Follow these steps to create a new e-mail profile in Outlook 2007 :
1. Click Start, and then click Run.
2. Copy and paste (or type) the following command in the Open box and then press ENTER:
control panel
3. If you are in Classic View, double-click Mail. The Mail Setup dialog box opens. Go to step 5.
4. If you are in Category View, under Control Panel, click Switch to Classic View, and then double-click Mail. The Mail Setup dialog box opens.
5. In the Mail Setup dialog box, click Show Profiles.
6. On the General tab, under When starting Microsoft Office Outlook, use this profile, click Prompt for a profile to be used, and then click Add.
7. In the Profile Name box, type the name that you want to use for the new e-mail profile, and then click OK.
8. In the E-mail Accounts dialog box, click Add a new e-mail account, and then click Next.
9. Click the appropriate server type for your new e-mail account, and then click Next.
10. Type your account information in the required boxes, and then click Next.
11. Click Finish, and then click OK.
Method 3: Delete suspicious messages from your mailbox
If there is a damaged message in your mailbox, you can resolve this by doing one of the following:
* Contact your ISP and ask them to delete any suspicious e-mail.
* Delete any suspicious e-mail by accessing your mailbox by using your ISP's Web-based e-mail program.
Method 4: Check your antivirus vendor's Web site for additional suggestions
If your antivirus solution includes an e-mail scanning feature, you may have to perform additional configuration tasks to use Outlook or Outlook Express with the antivirus e-mail scanning feature.
Antivirus software that is known to have caused this problem includes products by the following vendors:
* Symantec (Norton)
* McAfee
* Trend Micro (PC-cillin)
* Panda
Source: http://support.microsoft.com/kb/813514