Vanishing apps mid-use iPhone 4

Im having a problem with all the apps from the Applestore vanishing on my phone. I have searched and found others with disappearing app problems, but most seemed to be related to update issues or syncing problems. My problem is seems to be unique as far as I can research as they vanish while the phone is in mid-use.
Saturday morning (March 12), I ejected my iphone 4 (running iOS 4.3, not jailbroken) from my mac (running iTunes 10.4.1, on OSX 10.5.8) as normal and went to work. On the train I used several of my apps and all was working as usual. As I got off the train, I went to check in on foursquare and noticed that it was gone. In fact, all my applestore apps were missing. Three pages of folders, gone! All the apps originally installed on the phone were still there and working normally, but all the free and bought apps were no where to be seen. I did a hard reset and the apps were still gone. The phone seemed to be working normally otherwise.
When I returned home, I connected it to computer . It began to back up the phone and then did a normal sync. Under the apps tab, I noticed that all my apps were now unchecked, as if they had not been loaded into the phone previously.
Tried to restore from the most recent backup prior to the problem. But in the middle of updating and I got the message, The iPhone “MYNAME’s iPhone” cannot be synced because there is not enough free space to hold all of the selected items. Would you like iTunes to delete enough photos and photo albums from the iPhone to make room for the songs? How could that be if the backup was not that large? Even after getting rid of all my photos and movies, there was still NOT ENOUGH space for all the applications. That is strange and makes me think the apps that vanished this morning were still there but invisible and still taking up space. I then tried a factory restore of the phone, then backed up from an older back up (made two days ago when I updated to 4.3). Finished with full factory restore and back up. This seemed to work but interestingly enough, the back up restored everything including all the apps, but ONLY some of my folders (wouldnt it be all or none, as it is a backup from a time when the folders were there?). Also, only a few apps were in the few folders that were present whereas the rest were on the many home screens that followed. Spent an hour making new folders and reorganizing the 10 pages of apps back into 3 pages of folders. Things seemed to be okay for a while. Later that night, plugged my phone back into the computer before bed as is my routine. It backed up and did a sync as usual.
Sunday morning I ejected the phone and used it throughout the morning. The battery seemed to be draining fast, so in the afternoon I connected back to iTunes. I got an error message saying the phone could not be backed up. It asked if I wanted to continue on and sync the phone. I did. It synced. I ejected and then reconnected it to see if it would back up properly but the backup ran for more than an hour before I gave up. iTunes was stuck. I had to force quit and manually eject the phone. I restarted the computer and iTunes. Plugged the phone in again. Got a message that the phone was being ‘verified’, then after a few minutes, the backup proceeded and the phone synced as normal.
For the next two weeks, the phone operated semi-normally. The only abnormal behavior was sometimes apps would quit and I’d get the silver-apple screen that is shown during a reboot or shutdown, but this could not really be, as seconds later the home screen appeared. The only other strange behavior was the battery, which seemed to drain abnormally fast (at 2~3 times normal).
Two weeks later, on Tuesday (March 22), apps vanished again in mid use. Connected the phone to iTunes. Cancelled the backup and sync. Restored from that morning’s backup. Mid-way through the restore, I got the message again, The iPhone “MYNAME’s iPhone” cannot be synced because there is not enough free space to hold all of the selected items. Would you like iTunes to delete enough photos and photo albums from the iPhone to make room for the songs? Clicked yes. Then I got a new message, “The iPhone “MYNAME’s iPhone” cannot be synced because there is not enough free space to hold all of the selected items (1 MB required, 6.5 MB available). Would you like iTunes to turn off podcast syncing for this iPhone?” Said yes. But sync was not successful. Again, did a factory restore and backed up from the morning’s backup.
Something wrong with the physical unit? Has anyone else see this behavior?
iMac 24" Mac OS X (10.5.8) iPhone 4G 32g