Open the um.dat in /data dir in ultraedit, reset the bytes from offset 80
0:80 55 55 bc 7f 41 64 6d 69 6e 00 00 00 00 00 00 00
0:90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0:a0 00 00 00 00 90 6e 00 00 a8 01 00 00 00 00 00 00
Idea from http://www.tek-tips.com/viewthread.cfm?qid=51186