You're giving up too quickly! This is a common error because GCCG stores your username with a password on the first PC. The reason it doesn't work on your other PC is that you do not have that info (after all, would you want someone else to impersonate you?)
Simply put:
1) From the PC that works, copy the folder C:\.gccg to a flash drive.
2) On the PC that doesn't work, first delete the folder C:\.gccg. Then copy the data over from the flash drive.
Also, note that the administrators and mods of TLHH did not program GCCG. So you needn't expect them to be able to "fix" the program for you... but of course, we will try to help.