Dell OptiPlex's. Windows 7 Pro with the latest SP's. We are on a Windows 2008 domain with 80+ computers. I have 3 users that lose the ability to browse the Internet or connect to new shares via UNC or IP paths. We can ping all over the internal or external devices. We can resolve DNS. Any shares that we are already connected to continue to work. Cannot telnet to ports 80 or 443 in this state. Smells like malware but I have scanned with all the tools I know of and all comes up clean. The Windows firewall is turned off. To regain connectivity only requires a log off and on. Does not require a reboot. Once this is done connectivity is good until the next day at about the same time. I am not aware of anything running or triggering when this happens. Looking at task manager does not show anything interesting. Today I remove Symantec AV and installed MS security essentials to rule that out. Any ideas what I should look for would be appreciated. This is a weird one.