Can't level character from 3-4 if multiclassing

[Legacy_Mindslip]

               Writing this for a friend:

So I'm trying to take a level of ranger with a character who is currently at rogue level 3, I select all the necessary options and finish the levelling process to find... it hasn't leveled at all! It's still on level 3, with the prompt "Click Here to Level Up!" (or whatever it says). I can try infinitely to take a level in ranger, but it won't happen. I am able to take a level in rogue, but not ranger. It will always say I'm still at level 3.

System specs: http://support.apple.com/kb/SP644 <-- it is running on Apple hardware, but on Windows 7 for the OS.

GOG version of the game with alternate keys, English language.

Any bright ideas? '>
               
               

               
            

[Legacy_Dante2377]

               Is this a module (OC, etc)? or on a PW.  I've seen weird level-up behavior from various server haks that edit classes from that msg to "character has too many feats" messages.