I had this problem before, although I didn't know about the hold switch. It freezes after playing a song for about ten seconds, huh?
Reinstal Rockbox: that means replace AT LEAST the iPod file and the two original files inside the .rockbox folder. Delete all of the extra files in the .rockbox folder (eg. cache files). You might not have to replace any other files, but if the problem still occures, you prolly need to. And again, if the problem STILL occures, try reinstalling the bootloader.
The problem may have occured by messing with the Rockbox files, thus it just got screwed up. Hope this helps.