Ok since your at work you should print this all out..
Create a directory on your hardrive to save HijackThis.exe. A directory like c:\hijackthis. If you do not do this, you will not be able to use the backup/restore features.
Download HijackThis from:
http://www.spywareinfo.com/~merijn/files/hijackthis.zip . Then unzip the file to a floppy disk. Insert into the questionable system then place the hijackthis.exe file in the directory you just created.
Then run the program named hijackthis.exe. When the program opens click on the Config button, then click on the Misc Tools button, and click on the Check for update online button. When it completes checking/applying updates press the back button.
Now click on the Scan button and when it is finished click on the Save Log button. A Notepad window will open with the contents of this log. Click on Edit then click on Select all. Then click on Edit and then Click on Copy.
Then take the saved logfile and place it on the floppy.. When you get back to work come back online here and in this thread paste the logfile here for me to analyze..
Right off the cuff without seeing anything it could be a backdoor trojan not being detected.