My DELL xps M1330 Laptop having xp installed on it, is not starting. When I turn it ON, it shows the message that "Invalid Partition Table". I have important data on it.
So how can I run it and save my data ? I don't understand, what's the reason n why this happened to my laptop. May be this is due to virus attack.

Unless you had previous hard drive problems this may indeed be virus related.
Do you have the CD with the original Windows XP Operating System on it? If so insert it when you turn your PC on, go to setup, and go for repair.
Alternatively if you have a (stiffy) start-up disk you can check your hard drive.
What about a recovery disk?
With the little info you provided it is hard to make any other suggestions.
See "Similar Questions" to find possible causes.
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Alternatives : If you can get in, go to 'run' and type "cmd". This should get you to the DOS command line.
If not boot up from a: change to c: and type 'dir'. Check if there is a Windows directory.
Or type from either c: or a: "chkdsk/f" and let it check your disk - if still possible.
Or type from a: "fdisk". Just CHECK : do not really reformat, as all data will be destroyed.
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See also "Similar Questions" to find possible causes.
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If that all fails go to an expert. The recovery is most probably too complicated to do it yourself. Don't run the risk to destroy the data on your hard drive in the process...
:rolleyes: