Check the following key in the registry;
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User
Shell Folders\
Verify that these variables all point to paths that exist and especially the
Cache folder.
By default it should point to;
Windows XP;
%USERPROFILE%\Local Settings\Temporary Internet Files
Windows Vista and Windows 7;
%USERPROFILE%\AppData\Local\Microsoft\Windows\Temporary Internet Files
These paths can often be set incorrectly due to U3 and other jump-drive
software.