Hi there, not sure if you figured this out yet as it's been awhile but we had pretty much the same exact thing happening in our environment. The cause in ours was two different things..
The first thing I noticed the sessions would not reconnect when the user had a screensaver enabled and was running. I sent out a windows GPO to disallow CPU intensive screensavers and force only the blank screen saver, this fixed some of the issue for some users but was still happening frequently for others. The solution that seemed to ultimately work for everyone was to simply uninstall vmware view agent, reboot (yes really), uninstall vmware tools, reboot (yes still really), re-install tools making sure to UNCHECK the SVGA driver, reboot, install view agent and reboot again. Since doing that, everything been smooth again. I have a feeling that somewhere along the line vmware tools was upgraded w/o reinstalling view agent afterwards and that screwed up the SVGA driver.
I will try it out and on the next recompose.