I like my software up-to-date so I'm running Version 2011.0524.2259.39378 on my Windows XP.
No under/overclocking done on my ASUS Reaeon HD 4890 and it never crashes, maybe because I run m0mchil's miner at --frames 90?

Other info: 850 MHz (default clock)
2590 RPM (automatic control)
13v, doing ~71'C

Gives me around 91.918 MH/s [Rej: 37/1095 (3%)]

I could easly push it to 103 MH/s, but this makes it just too tricky.