hello czutshi,
i need some more information to help you with this problem,
1) are you trying to save the pdf off you web browser if so which browser and version (ie. Internet explorer 7.0, 8.0, firefox... so on)
2) have you tried to open mulitiple pdf. some pdf and be save locked to prevent you from being able to save it
3) what OS are you running on you system
thanks,
Thoughtlessmind