For questions and / or problems, it is strongly advised to read/register/ask PRiSM's FORUM. It contains many topics and answers that may help you solve your problem.
FAQ #1 : is PRISM a native 64 bit software ?
Answer : Not yet (as May 2011), it will be soon. Nevertheless all ASCOM drivers needs to be migrated to 64 bits, this needs to be achieved by hardware manufacturer. More likely two version of PRISM will be delivered : a 32 bit for controlling hardware and 64 for image processing. PRISM 32 bit version can allocate/use a 4GB RAM segment under 64 bits OS, and runs perfectly under 64 bit OS.
FAQ #2 : My anti-virus software reports PRISM.EXE (or setup.zip) as infected, what should I do ?
Answer : This is a false positive only reported by AGV, please check out Prism.exe using this wonderful tool : www.virustotal.com.
FAQ #3 : How many PC can I install PRISM ?
Answer : Three PC can run PRISM, but this is intended for a single user needs that may have several PC, like main PC, observatory PC or personal laptop ! PRISM cannot be shared among several users, this will violate licence agreement.