joke virus

This has been happending on my work computer. The virus does two things thus far in the 6 times I have had it. First, it takes over the start menu where if you move your mouse towards the start menu, the start menu moves and you are unable to click and get into it. The second thing that it does, when your in any program, whether your in internet explorer, msn messenger, your e-mail account, or notepad, it starts typing random letters and numbers. I can get rid of it temporarily using trend micro house call, but it comes back every week or two. Please help. This has become a real problem for me and usually keeps me from using my computer for a minimum of a half day of work or longer. This is a Windows XP pro computer.