-System hang-up. I never know when this happens, unless I check my phone during charging or place it on the charger. Basically, the phones works normally but if you place it on the charger, it won't charge. If it's charging, when you take it off, it says it's still charging. Then, cycling the data connection causes the device to catch up (including notifying you of the missed texts and calls that it failed to notify when the phone hung-up) but even better, the device won't charge when this happens. My belief is something in java fails as I hear 2.x doesn't have this bug.
-WFi. Sometimes it doesn't auto-connect until I open the menu in the top menu.
-Browser: Sometimes, if searching on Google, the search entry will allow me to type but hitting enter or search does nothing. Instead, I need to always use the browser address bar to make sure this doesn't happen (though I forget sometimes). Also, sometimes I'll come back to a browser card and it's blank. Reloading does nothing (though I suspect this is more of a memory optimization issue).
- Sound. PulseAudio failing is just unexcuseable and I feel as though a decent beta testing could have revealed this problem before shipping devices. Even better is how this still hasn't been fixed by HP.
Although not a bug, my biggest gripe has been the laziness of both Palm and HP to optimize the vm settings. What took me, a mechanical engineer, a week of testing allowed me to discover the vm settings which not only stopped the lock-ups I suffered (the Pixi has no processing power so making Linux clean the vm at such low ratios makes the device crawl) but improved stability where I'd get weeks of uptime now. At least this I could fix. The other bugs I listed not so much...