and it still is because the poster never returned.
Please do this;
1] With an empty desktop, (eg no windows open and just the Taskbar and any desktop shortcuts showing), take a screen print of the whole Desktop, save it as a JPEG file, upload that to your favored image hosting site then give us a link to that image.
It may help us see more.
2] In that other discussion more advice was given about tools to use, (AUTORUNS AND HiJackThis) which might help you pin this down.
3] Also, a link was provided to Then Please try This - CNET Spyware, viruses & security Forums, which is a comprehensive guide to run utilities to root out any malware.
As was said in that post, this issue is not well known and in fact I haven't seen it before, so at this stage we are as in the dark as you are, so more work needs to be done.
I have a text box that appeared the other day. It is about 1 1/2 inches by 5 inches on the bottom right of the monitor. It is always on top. Does not appear in safe mode. I have closed all processes until windows crashes without it going away. It appears to be part of the start up menu but msconfig does not show anything in startup that shouldn't be there. There is a similar thread in windows 7 form and a screenshot that is identical to mine. The link is http://forums.cnet.com/7723-19411_102-545274.html Not showing on any antivirus or malware scans and rkill found no malicious processes running. I am at the end of the limited knowledge I have. It is a real nuisance.