As I found out to my peril, installing WMF 3.0 (including powershell 3.0) is a bad idea on Exchange 2010. I tried and it knackered my exchange install. I had to follow steps to sort it out (didn’t take backups as normal DOH!!)

1. Shutdown original VM

2. Reset computer account for exchange server

3. Build a new VM with the same name and drives layout

4. Run the Genius prerequisites script by Bhargav Shukla found here

5. Run the exchange setup exe with switches

   D:setup.exe /m:recoverserver
   

6. and relax

further details on the on the wmf issue and possible resolution timescales