All I can think of is that your browser or computer is not retaining the UHM cookies that allow you to go back to the site and be logged in.but if i leave it for a day, overnight, or even a couple of hours, I still have to faff around logging in again.
As you can get back within about 30 minutes does that include closing the browser and opening it again?
When you cannot get back without logging in again, have you shut down the computer or just the browser?
Do you run any cleaning program such as Ccleaner or other software program?
I have just tried my IE browser and got onto UHM straight away and I have not used it for a couple of days.
dave