I've got a ATI Radeon HD 4300 / 4500 series.
It keeps on crashing on most games and makes my computers fps lag like hell.
It started about a week ago.
I've had this computer for about 5 years.
I've upgraded drivers and everything. :L
R.I.P Your card. Use MSI afterburner and open a game and see what load it gets to (% used) when it crashes. If it crashes because it's hot, get a few more/better case fans, if it crashes because it's at high load, it's toasted like... well like toast.