Please let me know which product are you using and I will move this thread into the appropriate product community.
It sounds like the roaming profile has become corrupted on the local machine. Could be be a virus or malware. Try to run a command line Scan on the machine. Download win_betaengdat.zip from the threat center http://vil.nai.com/vil/virus-4d.aspx. Run this command in safemode at the command prompt scan.exe /clean /adl /all /program /unzip /rptall /report=c:\scan.log This could take a couple of days if this doesn't work. Then I would need to backup up mydocuments, Favorites, Outlook history and remove the profile and create it again.
Hope this helps