No. 1 -- You fail to thoroughly test your new releases, then delete any problem posts from your tech forum.
No. 2 -- There's not enough interaction between front-line technical staff and the engineers, so a problem goes for 3 months of "we haven't changed that" and then ends with a message from engineers with "oh, yes, we did."
No. 3 -- Your documentation hasn't been properly reviewed for a new release, so it contains suggestions that haven't worked for two major releases
No. 4 -- You have 'modular' products where you don't have to include all the pieces, but things are a bit strange if you don't. They're also problematic if you do, because you have to provide for customers that haven't bought them all.
No. 5 -- 'Upgrading' turns a functional testing machine into a nonfunctioning lump of silicon that needs to have its OS reinstalled because it is so far beyond being repaired.
Nos. 1 and 4 are my favorites. The fourth one, describing the modular product pitch, really hit home. The challenge with "marketing modular" is the modules become moving targets, updated in collateral and client pitches as frequently as new functionality can be dreamed up by management. Do everyone a favor and first make sure you have the architecture in place to support your wild-eyed quest for more market share.
OK, I'm done.