Suspected virus in C:\Windows\Temp area

Dear all,

I have a Windows 2003 server OS, and Im sure I have a virus which is not
detected by my AV Solution - Trend OfficeScan product.

It first appears as a process in TaskMgr for example LA5819.exe - this file
is also apparent in the C:\Windows\temp directory. Thus I can only remove
the file when I kill the process.

However, within the next 5-10mins a new file with a completely different
name appears....

Has anyone heard about this?