My system was working fine until three days back, it started giving me problems....

Configuration is:
P4 1.7GHz
Windows XP Professional
Harddisks 200GB(Primary) and 80GB(Slave) are being used
Mercury Motherboard
Drives Present: C,E,F on Primary and D,G,H on Slave

Whenever i start my computer, it takes a long time and then starts scan disk and asks if it can scan my H drive. I let it continue but then is comes up saying that H is a non win xp drive and that it'll not continue. Then continues to start Windows... Takes a lot of time and then hangs up at the startup screen and then starts after 10 minutes. And then pops a message from the System Tray saying that "Windows was unable to connect to all drives"....

I thought maybe some files were corrupted and so used Acronis True Image and restored an image which was 1 month old... To my utter surprise... The problem still continues... I presume that the problem might be with the power supply cable ot data cable but i'm not sure exactly...

I tried even removing my 80GB Slave Harddisk hoping to solve the problem but it is still prevailing.... I'm desperately behind my computer because all my project files are stored in H drive... Please help me...

Try scanning all your partitions from the Recovery Console.

You will want to execute the following command for each partition: For example:
This will scan all your drives for file system errors or bad sectors. It is possible that, for one reason or another, your partition got corrupted.

I have seen that before, I was able to fix by going to run/cmd

and then run chkdsk from there. It will run then at next boot up, and fixed the problems after it ran.

Actually, the chkdsk from Recovery Console is a much more rigirous check than the one run from cmd. Try running chkdsk from Recovery Console