Hi Abhinandan,
I have got few questions to you before giving any suggestion to your problem.
Do you have any Internet connection to your machine?
Do you have any Anti virus installed in your XP?
- If yes is it up to date in virus definitions?
Did you update ubuntu regularly (all the patches/updates etc)? Generally it automatically prompts you to install, you have to allow it to install them.
If you are using windows, you have to got an anti virus software which is up to update -- This is blind fold rule 1
If you want to use ubuntu to its extreme, you need to have an Internet connection which can be accessed though ubuntu 
(Some Dial-up connections are not recognized by ubuntu due to lack of h/w support i.e. modem support to Linux) -- This is blind fold rule 2
For disabling autorun for drives in windows you can erase the autorun.inf file by below steps.
1. Start your XP in safe mode/safe mode with command prompt (F8 or F10 while booting windows)
2. Go to C:\ in the command prompt
3. Try giving the below commands one after another
Code:
attrib autorun.inf -S -H -R
Code:
echo '' > autorun.inf
Code:
attrib autorun.inf +S +H +R
4. Repeat the step 2 and 3 for other hard disk drives as well to disable autorun.
PS: You can straight away delete the autorun.inf file in safe mode, but viruses generally have tendency to recreate them.
I am not saying this is the only resolution to your problem, but this is one of the way in which I have solved this problem once.
C ya.
Guys, Please correct me if anywhere I mentioned anything wrongly.
