(xenpci.sys causing was issues in this partiular case, but this should solve any driver oddness and get booting again) 

1) Load startup repair

2) Get to a command prompt

3) Load regedit and pull in the System hive from c:\windows\system32\config\system

4) Set find services in the controlset01 (or whatever you think the current one is if unsure, or all of them)

5) Set pciide services start to 0 (boot)

6) Delete any weird storage controller services entries.

7) Browse to classes in the hive

8) Search for upperfilters and lowerfilters and if any of the services just deleted are referenced, delete the upperfilters/lowerfilters entries.

Reboot. Profit.