I have vSphere plugin 0.9 and Jenkins 1.462 (and I tried 1.463) and it caused matrix jobs, that do not run on vSphere slaves, to die with this error:
Started by timer
To add insult to injury, the builds then got locked.
None of the vSphere slaves seemed to be having problems (in fact, jobs were building on them just fine).
My solution was to change all my vSphere slaves to normal slaves and then removing the plugin. Simply changing the slaves wasn't enough.