My guess is that something in your login script is telling Windows to open the grouplist file (I assume it is grouplist.csv and not grouplist.cvs as you posted). At that point what ever program is associated with the .csv extension will try and open the file. You can test this theory by changing the file association to notepad or something else. Find a .csv file and right click. Then choose Open With. Select Notepad and choose Select default Program (or something like that). Then select Notepad from the list and make sure always use selected program to open this kind of file is checked. Then try to log off and log in again and see if notepad opens the file instead. If it does, then you have an issue with the log in script and you may want to post that script. You can follow the steps above except choose Calc in place of notepad to revert back to the current setting.
-Bear
