Try hitting the knowledgebase for a Tech note on 'optimise CS4 Windows 7', it'll run you through a list of checks that usually 'fix' crashes like the ones you describe
This ARTICLE will give you some tips on cleaning up your computer and getting it ready for an editing session.
Also, do you get any error, or warning messages, when PrPro freezes?
Usually, when a program hangs, or crashes, there is a "breadcrumb trail" left behind, and Event Viewer will possibly give you some clues as to what was happening with your system, and/or the program. This ARTICLE will give you tips on finding those clues.
Some reading about Win7
Win7 Help http://social.technet.microsoft.com/Forums/en-US/category/w7itpro/
Win7 Configuration Article http://windowssecrets.com:80/comp/100218
Win7 Monitor http://windowssecrets.com:80/comp/100304
Win7 Optimizing http://www.blackviper.com/Windows_7/servicecfg.htm
Win7 Virtual XP http://www.microsoft.com/windows/virtual-pc/
Win7 Adobe Notes http://kb2.adobe.com/cps/508/cpsid_50853.html#tech
Win7 Adobe Update Server Problem http://forums.adobe.com/thread/586346?tstart=0
Win7 Photoshop http://forums.adobe.com/thread/511916?tstart=0
do you think you can send me a link? I;m having trouble locating a tech note which addresses premiere pro with windows 7.