Communication errors when iPod 2nd gen connected to car stereo

Question

So a while back I ultimately decided to update my 2nd gen iPod touch from iOS 3.1.3 to the highest it'll support, which I believe is iOS 4.2.1. The update went fine, and everything seemed to be working alright until I plugged it into my car's stereo as I normally do while going to work and back. I'll detail the problem below.
The stereo is aftermarket, a Pioneer unit, which is probably considered really old by today's standards but for me it still works beautifully. I plug the iPod in via the USB port it has. Before updating the iPod, there were no problems. After the update, specific songs on the iPod will trigger an "Error-19" to display on the screen of the stereo, and all control of the iPod ceases to function. The error refers to a communication error of some sort between the iPod and the stereo. Now the strange thing is that even though this error pops up, the iPod will continue to play the song that caused the error and proceed to the next track when it's done. I have my iPod playing on shuffle so when this error comes up I have to wait for the song to finish and hope the next one doesn't trip the error again when I unplug and plug the iPod back in. Doing that while the song is still playing just produces the same error. Ifthe next track is fine, plugging it back in restores all function.
So while this error isn't the end of the world, it's a brain teaser that's been irking me for a few weeks now. I'm hoping someone may know if something within iOS was changed between 3.x and 4.2.1 that might cause this type of communication error to come up. I originally thought it may have something to do with ID3 tags and some rogue setting that confuses the stereo when it's sent over, but I couldn't really find any major difference between songs that work perfectly fine and those that cause the error to show up. I'm at a loss here so any isight would be appreciated.
Also of note, I am aware that upgrading to a newer stereo or newer iPod will undoubtedly fix this, but I don't really have a need to spend money replacing equipment that is still in working order. Thanks for your time.

Answer 1

Sometimes this works:
- Reset the car system
- Reset the iOS device. Nothing will be lost
Reset iOS device: Hold down the On/Off button and the Home button at the same time for at
least ten seconds, until the Apple logo appears.
- Reset all settings      
Go to Settings > General > Reset and tap Reset All Settings.
All your preferences and settings are reset. Information (such as contacts and calendars) and media (such as songs and videos) aren’t affected.
- Restore from backup. See:                                 
iOS: How to back up                                                                
- Restore to factory settings/new iOS device.             
If not then contact the Pioneer. Maybe there is a firmware update available for the car system.
Yes, other users have reported that updated to iOS 4 broke compatibility with some care systems.