Not sure if this is your issue. Are you running FireFox? There is an Xmarks bookmark syncing service addon that may be causing the issue. They recently shut down their servers: Xmarks Shutting Down Syncing Services at the End of 2010 - Tested
If you are running Firefox, you could use Tools/Addons to uninstall it. You could also check Addons in IE and check in Control Panel\Programs and Features.