reaper has stopped working

Hello people, Recently I have not been able to make music do to the fact that Reaper stops working every time a song loads or I press play. Vista tells me "A problem has caused the program to stop working correctly. Windows will close the program and notify you if a solution is available." This started just two days ago, after I had been using the recent update from the 15th with no problems. I fear it has something to do with free VST instruments I've been downloading. In effort to solve the problem, I ran a thorough antivirus and antispyware scans, in addition to reinstalling reaper and deleting all the new VST instruments. I run Reaper on an Acer Aspire 5100, Vista 32bit, AMD Turion 64x2, 2G ram, Presonus Audiobox USB and EZDrummer. Why do I have this problem and how can I fix it?

update 

It's been three days and no one has been able to offer any insight. The good news is that I think I fixed the problem simply by deleting all VSTis and restoring Reaper to default settings. After reinstalling the plugins and changing the settings, everything has been stable for 2 days.

Hi osprey, probably the reason nobody responded is that this is the less visited compatibility forum. But the steps you took are the right thing to do :)