I've installed .Net 2005 and 2008. If I install build 1151 both 2005 and 2008 work ok. I then installed build 1154. On startup, both 2005 and 2008 start to issue dump reports and this happens everytime I tried to use .Net. I tried rebooting and the problem still persists.
I uninstalled 1154 and put 1151 back on and now, 2005 and 2008 run ok.
I can't say for sure that 1154 has caused a fatal runtime problem that 2005 and 2008 can't recover from but I thought you might want to know about it in case it can be replicated. By the way, I've installed the .Net service packs.