First thing to try is always a battery pull. ANY wonky behavior should be met by a 30-second battery pull.
Normally, 507 means the OS is corrupt of missing and needs to be re-installed. Honestly, a battery pull probably won't help, but it's worth a try anytime. You can download the latest OS version from the sticky at the top of the 8800 forum, but be sure to choose the one specifically for the 88
30.
Follow the instructions in the FAQ to the letter, remembering to delete that pesky vendor.xml file.
How do I upgrade the OS on my BlackBerry? - BlackBerryFAQ