Data lose on iMac with snow leopard

[MacIntel]

Data lose on iMac with snow leopard. Everytime i shutdown my iMac some or the other data is lost. What may be the problem. The most recent files and folder gets deleted first. Please help. I don't know what happened. I dont want to keep loosing my data...

[Patio]

Data loss on a iMac? Thats not possible!! Does it happen on every reboot? How did you know that there is this kind of problem on your mac? I dont think this is a problem and something like this can happen... Might be you have deleted the files and later forgot about the same. Did you make sure this happens automatically?

[MacIntel]

I am not insane! I know this is a weird kind of problem but it is happening for sure and automatically, i'm not deleting any files. Just to make sure, i created a new folder which is empty and then i rebooted my iMac. Now on reboot the folder is gone... Please help. It happened that after i closed safari, i was asked to type in my iMac's root password, i don't know for what, but after that i started getting this problem. Can anyone help me...?

[Noverism]

It feels like its some kind of a virus in your system. But its hard to believe! Well if you don't know what is happening and what process is asking for password how can you enter your root password? Well Mac systems are secured and any access to system files and settings needs to be accessed as root, so may be there was a virus which asked you type in the password and now its just eating up your files. May be this is not the case but who knows. Its better to reinstall Snow Leopard again...