My HTC Tattoo loses its mobile broadband connection after a couple of days without a restart. Calling and SMS still work but no data connections. Disabling and reenabling the mobile data connection does not help. Only with a restart the data connection can be used again. Is there a solution to this problem?
I do suppose you went to Settings > Wireless & networks > Mobile network settings and have "Enable always-on mobile.." checked on?
Smartphones, like any computerised device, need to be power-cycled regularly in order to function properly. Lots of things get cleaned up by this. If you leave your phone on overnight to use the alarm to wake-up, just power-cycle your phone as soon as you're up. It will be fresh for the day.