Since I installed Seasons, I cannot get into any house with any custom careers  or custom majors in the downloads folder. I have uninstalled and reinstalled S2 and expansions, created new neighbourhoods etc.
I have the following Careers and Majors:

Career               

Nurse                     
Education                           
Psychic                        
Star Fleet                        
Priest                        
Priest Teen                     
Star Fleet teen                        
Alchemy adult                        
Alchemy Teen                        
W&W Adult                     
W&W Teen                        
SF Car Banking                     
Movie                        
Rock Musician                     
Cryptozoologist Teen   
Cryptozoologist                        
Accountant   
Teacher                        
Music                     
Alien Investigator   
Casino                        
zzzzzReal Estate                     
Racing                     
Hacker                  
Hacker Reward                  
Drug Dealer         
Playboy         
SimandGabanna                  
Writer Adult               
Painter adult                  
Painter Teen                  
Writer Teen                           
PirGun                     
Pirate                     
Paraphychologist                     
Vampiric                     
Dance Teen                  
Archeology   
ChildCare Teen                        
Pet Teen      
Fashion   
Fashion Teen   

Majors                        

Alchemy                     
Archeology   
Cosmetology               
Dance   
Education   
Fashion   
Firescience                  
Global Warming                     
InuYasha   
Jedi                  
Marine Biology                  
Paranormal                  
Potions                     
PSI                     
Stripping                     
TheatreEd                     
Witchcraft   

All have separate ids etc.
S2 Seasons with update and ep1-5, sp1 and 2 and Happy Holiday stuff