Have you tried:
– deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the Twenty Eleven theme to rule out any theme-specific problems.
– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems.
– re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress.
I switched over to twenty ten and it still didn’t work. I will have to deactivate the plugins one at a time in order to isolate the problematic one. I’ll try that first and then move on to the other suggestions if that doesn’t work.
Update: As it turns out, it was the Jetpack plugin that was the culprit. I have since posted in the support forum for that plugin.
