iPod Touch - some apps randomly stop working, some music disappears

iPod Touch 2nd Gen (when bought online, Amazon said it was 3rd gen )
running iOS v 4.1


for those that dont know, my mac has had a hard crash - and i've only just managed to install iTunes on my Thinkpad.

my iPod Touch is configured for manual mode - ie i can transfer music to it from any pc.


i have not upgraded any apps or the iOS, all that has changed is instead of syncing the iTouch with iTunes 10.4 on OSX 10.6.8, i have synced it with iTunes 10.5 on XP Pro SP2.


and i have just noticed that alot of apps have stopped working - i cant seem to work out a pattern.

maybe its apps that i havent used for a while, at least before the mac crash. thing is though, i wasnt using any apps during my first pc sync. maybe if its apps that had already been used, ie loaded into the iPod system memory - ie they stay in the background???



i tried re-booting, but that made it worse:


apps working before re-boot:

music
photos
clock
notes
facebook
grindr
five or more
calculator
ibooks
videos
youtube
safari
ebay (but more buggier than usual)
maps
mail
weather
drinks tracker
app store
nike + ipod
voice memos





apps not working before re-boot:

funny pics
Apple Remote
Tonepad
Kiss KUBE
Fart Piano Free
drum kit lite
easybeats LE
justinbieber
toobz-free
dots free
tictacfree
labyrinth 3d
angry birds
wordsearch
sudoku
unblock free
block touch
glow puzzle
vector runner
iPint
tunnel
glow pong lite
up and away
falldown!
bubblefree
gearslutz
symtrend
IQ test
Autism XPress
Autism Test
drinks
drinks free
battery
ihandy level
remote mouse
strobelite
groupon
glowtouch paint
convert units
oscillatr pro
uhear
ohmEE
soundscope
hearing check
bpm
metronome


post-reboot apps working:

Music
Notes
calculator
clock



also, another problem is that some of my music seems to have been deleted from the iPod Touch: however, its not music i have purchased in the iStore as you might expect, just the odd mp3... most of which are live recordings from live gigs, and one Leftfield track.... starting to get really annoyed...