Multiple sync problems

Question

I just got a new Dell laptop with Windows 7, and ever since I've had multiple problems syncing with my first generation iTouch. We tried downgrading to iTunes 9.0, because my husband read that it could be the source of the problem, but it hasn't worked.
In the beginning, it removed all of my apps every time I synced. Now, the apps are there, but all my music is gone.
When I connect, it locks up iTunes for several minutes. Sometimes it will see the iTouch, other times it remains locked up. When it does see the iTouch, it says it can't sync because of an internal device error. However, it is in the process of syncing while this message is up. And the iTouch screen is normal, not the typical one that says it is syncing.
Despite these issues, I was able to sync daily, to get my new podcasts each day. However, this morning, it removed all my music, and all my podcasts.
I have tried to restore; no luck. I tried establishing it as a new iTouch, and it looked like that was going to work. However, all the songs gave an error message saying there was a problem with the file. When I clicked on the songs in iTunes though, they all played fine.
I'm at wit's end here! I don't want my iTouch to be a worthless piece of metal and plastic! Please help!

Answer 1

Once again, I am having iTunes set it up as a brand new iPod. It is trying to load music onto the iTouch, but with every file I'm getting an error message. The music plays fine in iTunes, so the files themselves are fine. The error messages are:
Could not copy _______ to the iPod Sharon's iTouch because an unknown error occured (-48).
iTunes could not copy the file ________ to Sharon's iTouch because the file could not be found.
Could not copy _______ to the iPod Sharon's iTouch because an unknown error occured (-42).
I tried a full restore again. It wiped all the software from my iTouch and reinstalled it. When it was done, instead of selecting "set up as new iPod" as before, I tried to restore it with the backup from my March 29 sync. The error message said:
Could not restore the iPod Sharon's iTouch because the backup session failed.
So, I selected the option to set up as a new iPod, but chose not to automatically add music. Then, I went to the music tab, and selected one artist, and started a sync. It added the songs from the artist list, but not from the playlist.
I added more artists, and started another sync. While it was syncing, I got the message:
The iPod Sharon's iTouch could not be synced because an unknown error occured (-48).
However, in the background, the iTouch continued its sync.
Then, I got the message:
Attempting to copy to the disk "Sharon's iTouch failed. An unknown error occured (0xE8004006)
When I clicked ok, this message came up a few more times, then:
The iPod "Sharon's iTouch" could not be synced, because an internal device error occured.
The sync stopped then, and I had only the 3 songs I managed to get on in the previous sync. I tried another time, with fewer artists, but the same thing happened.
Then I tried to sync just my apps. I got the message saying it couldn't sync because the required file could not be found, but yet it appeared to be syncing anyway, according to iTunes. But unlike the previous two sync attempts, my iTouch screen remained black - no "syncing" with the battery icon, as there should have been. I was not getting the constant change in the size of memory on my iTouch this time, though, which was progress.
At the end of the sync, I got a series of error messages, including too many files open, internal device error, ect. After clicking through them all and turning on my iTouch, I saw that despite all the errors, all the apps did sync and are now on my iTouch.
Now, I can't get it to sync at all again. So I have my apps, and 3 songs, only the podcasts I can download directly to the iTouch.
I am completely confused.