I'm experiencing a strange issue here. Internet Explorer 8 (on a large number of XP devices) seems to have stopped loading applications that some URL's target (for example, a TeamSpeak server link "teamspeak://" allowing you to join a channel by clicking on the link as long as TeamSpeak is installed).

The issue is with our CentraStage support software. Clicking on an RDP or VNC remote session loads the usual IE window saying "Do you want to allow this website to open a program on your computer?", but clicking on Allow simply does nothing. It was working normally on Friday, and it's not a CentraStage issue as other users here at the LA can use it fine within IE. I have also tested it in Google Chrome and Firefox and it works normally. No errors in Event Viewer, nothing in the CentraStage log, nothing in the AV log. Everyone's PC's were off over the W/E and there were no software roll outs, updates, patches etc applied - I'm really baffled!

Does anyone have any ideas why this is happening or what could be causing it?