Generic Network Failure

[vividrich]

My wife just got this message on her VX today; and while regular texts went fine pictures could not be sent or received, they eventually errored out with the subject message.

Google told me HTC phones have experienced this for quite a long time (and I think I remember it happening to my Aria as a matter of fact). Clearing the messaging app cache and rebooting cleared it up, but one thing I couldn't find is WHY it happens?

Curious more than anything.