Hi and welcome to Apple Discussions.
Have you ever successfully synced the iPod touch with that computer?
Make sure the iPod is directly connected to a USB port on the computer, not a USB hub, monitor, or keyboard.
Also, make sure you have the latest version of iTunes installed on the PC. You can download it from here: http://www.apple.com/itunes/download/.
If the issue persists after directly connecting the iPod and updating iTunes, try the general tips in this article: http://support.apple.com/kb/HT1207.
Don't know if you've gotten an answer to this yet, but I was having this exact same problem with my 4th gen iPod touch (a session could not be started with the iPod Touch). I went through the steps Apple gave, about deleting the saved back up file and syncing the iPod again, but that didn't work either, i couldn't restore to factory settings because it need to back up, which it couldn't do.
What finally worked was that I completely shut the iPod down, you know holding down the button on the top to power it off, and I let the iPod restart and then connected it to my computer to sync it, and no more error message. Because I had already deleted my back up file, it took a few minutes because it had to create a new one....but the error message is gone and the sync went through perfectly.
Hope this helps.
Try connecting your ipod to another computer and sync only 1 file or song just for isolation purpose only to see if it'll sync.
If still not syncing, then porbably you may have a bad iOS installed in iPod which is hard to see if it has a problem because you said nothing's wrong with iPod. I just saying is, it MIGHT have a bad iOS.
If you are unable to do a restore, put your ipod in DFU mode, then connect to iTunes and iTunes will detect your ipod in restore mode. Press shift key (PC keyboard) then click the restore button on iTunes. I hope you have your copy of IPSW file for restoration purposes.