I am not sure what happened, but I noticed, that when I connect to VC with VIclient, everything works ok (permissions), specified accounts can connect to their VMs, open console and else. But if they login via https://IP_vCenter, and login with their username/pass, then they can browse VMs, and such, but when they open console (with browser) then browser (FF, IE) stops responding.
Did anyone saw such problem?
What version of vCenter are you running? I saw somewhat similar behavior with vCenter 4 and the Remote Console plug-in. The user had rights to connect with the VI Client and see the console, etc. But when trying it through the web interface they could get to the remote console screen but it wouldn't start. It wouldn't freeze the browser, but the remote console would never open. It turned out to be a permissions problem and I had to assign the user permissions at a higher level than the folder in order for it to work. I never did figure out exactly what permission was needed though.
Try assigning basic rights at the top level and then try it again. Keep increasing rights until you find which permission you need.
Hope this helps.