HELP! unknown error occurred (-48)

[Demonskyline]

hi. i had my 5g 30gig ipod video for a few good months now. i have windows xp and itunes 7. about an hour ago, i connected my ipod in and on the bottom right of my screen an error showed up:
"iTunes:iTunes.exe - corrupt file
The file or directory \iPod_Control\iTunes\iTunesPrefs is corropt and unreadable. please run Chkdsk utility." i runned chkdsk twice, no help.
after i ignore that, an error message keeps poppoing up in the window saying:
"The iPod "Dropstar" cannot be updated An unknown error occurred (-48)."
this error keeps showin up although i didnt try putting any songs on or anything.
im not sure how this affects anything, but i have a lots of songs on my ipod and if something happens to them, ill be doomed. also i cant find any good backin up software, and i dont a lot of space left on my hard drive anyway.
help will be GREATLY appreciated.
thanx in advance.
also heres a screenshot of what happens RIGHT away when i launch itunes:

[Demonskyline]

i tried updating everything using apple software upadte. i also tried reinstalling itunes and im going to try again right now. by greatest worry is that im going to lose my data on my ipod. please help me...

[Demonskyline]

ANYONE? please...