I saw your post and figured this may be a good place to start. I've been frustrated too with the crashes lately. I'm running Win XP and ProTools 7.3LE on an ASUS motherboard, AMD cpu, and 4 gb RAM. I'm trying to run a couple of plugins (Addictive Drums & Keys) and Reason 4) and can't even get through laying down the tracks for one song before I start getting crashes and it stops recording.
I had more or less the same problem with Cubase 6.5 on Win XP and finally found out the cause of the trouble: it's the amount of RAM that is not sufficient
for running Addictive Drums within a RAM-hungry DAW, especially not in combination with Addictive Keys.
While everything still worked wonderfully with Cubase 5 Essential, things stopped to work flawlessly when I installed Cubase Artist 6.5. The reason was simple mathematics: Cubase Artist 6.5 in combination with Addictive Drums required more RAM than XP could deliver.
I'm pretty sure that your crashes will cease once you move to Windows 7/x64 and install at least 8 (better: 16) GB of RAM. This was the case with me, anyway.
However, I don't know whether your old PT version will run on Windows 7.
The step from XP to 7 was not an easy one for me, so I do understand if you should hesitate. But you won't regret it once you've installed W 7 and made the necessary settings to optimize it for audio/recording purposes.
So, you might want to consider spending some money on updates/upgrades for the sake of creativity and peace of mind.