Moved from Home Products to VirusScan Enterprise for better attention.
What are the On Access Scan setting for scanning files set to? looks like the files may have been hung on scan so it times out. normally it is set to 45 seconds. Try bumping up the time some more and see if it fails. Are you scanning zip files? sometimes if the zip file is password protected it will time out. Try unchecking scanning inside archives and see if it helps.
I would say that this is the scenario when McShield and some other program quasi deadlock each other for a file's access. If I remember correctly this error message has further information on the file in question. You might decide to exclude that file from scanning if it is not really prone to infection and/or frequently used by one of your important programs.
The other message, i.e. Mcshield termination is related to this previous error.