I'm not sure if most people know this or not...
Many people complain about the T-mobile Dash, or the T-mobile Wing randomly crashing or freezing up. And there is actually an easy fix for this. These devices run off of the Windows Mobile Operating System.
And when an application is closed(whether its contacts, media player, or IE) it is still left running in the system's memory. When you hit that little 'x' in the corner it just minimizes the application much like a normal Windows PC operating system. And when the device is left running for a day or so those 'minimized' applications start to eat away at the available system memory.
So all you need to do is make sure that after a period of use with one of these devices it is necessary to access your options>memory options and close some of those unused applications. Then you should notice a large decrease in your HTC device freezing or slowing up.
current handsets--BB 8100, And not sure what to buy next...mabye the Sonim Xp1? http://www.sonimtech.com/features_xp1.html