I get random 'crashes' were Altium just stops
I have actually found Altium to be very stable - in fact I can't remember the last time it crashed on me.
Some important things to remember:
1/ Altium is very clear - the software is tested with Intel processors ONLY. Therefore you may run into problems when using AMD processors;
2/ Altium give no guarantees when running under virtual machine conditions (ie VMware);
3/ You should have a video card with 1GB (or more) of dedicated memory;
4/ You should have 3GB of usable RAM for Windows 32 bit installations;
5/ You should have 8GB of usable RAM for Windows 64 bit installations;
6/ Do not use Windows Vista as it is quite unstable within itself.
Follow these guidelines & you should find that Altium is one of the most stable programs available.