zune software wont open?

ok well i had been having some problems with zune software for a while and esterday when my sister put ms points onto her account she could not sign in when she opened the software (she put the points on via the zune website) so i had to change her password and stuff but then when she bought the songs whe they tried to download it said some kind of error occured. It was somekind of error about zune pass which we dont have so i looked up the alternate cause and did the drm change thing and still nothing. So i udated the zune software and at the end it says it needs to restrt your computer so i did and when it came back up the software wont pen it just shows a little box that says you must restart your computer after setup. I restarted the computer like 6 more tims and nothing. I unistalled the software and reinstalled it and the same thing happens. Please help.