Grey Screen on PS 4.5 servers, in the Citrix XenApp / Presentation Server forum on BrianMadden.com

I've been chasing this for a while without any resolution. The issue is that after nightly scheduled reboots certain servers (Random) would be at a grey screen. They would appear to be completely up but you could not interact with the session or connect via rdp or ica. Rebooting the server would resolve every time.

I've seen various MS hotfixes that address the issue or something similar. I stumbled across the this KB article KB930045 which references problems rebooting servers from within a remote console session. I tend to do most of my connections to the citrix servers using rdp /console so often times I'll have a disconnected (or connected/idle) session open on various servers. I went through the farm and made sure that there were NO console connections and I've begun to use ICA connections to the servers for routine stuff.

Since I began this I have not had a single instance of the "Grey Screen" on the servers. I DID NOT install the hotfix. This may be dumb luck or it might have something to do with The Citrix servers rebooting nightly AND having a remote session open/disconnected/idle/whatever when the reboot is initiated.

Just my 2 cents that may help somebody else.