ok, whenever i open my command promt through Start > Run : cmd it opens and then closes...

this was happening to me before with Hijackthis and someone gave me something to delete something.. and it worked..... yah..

I don't understand that sentence. Could you explain more?

If you deleted something with HJT and your problem started, then you should be able to restore what you deleted if you have HJT configured properly, as per the Preperation Guide here at Bleeping Computer.

To restore a deleted entry:

Start HJT, and go to Config...> Backups
~~~~~~~~~~
To configure HJT to make backups start HJT and go to: Config > Main > place a check next to: Make backps before fixing items

The type of behavior you describe is typical behavior of some viruses/worms such as W32.Klez, W32.Yaha and W32.Spybot.Worm. You should start by performing malware scans to remove possible infected files.

Perform these online Virus scans:
[Watch the Address bar in IE. You may receive alerts that "This site might require the following ActiveX control...Click here to install...". Click on that alert and then Click Install ActiveX component.]

Trend Micro Housecall Scan
Panda ActiveScan [ActiveScan Panda does not remove adware/spyware but will autoclean for viruses & worms.]
a-squared Web Malware Scanner

If not malware related, another possible solution can be found in the last post here.

i ment that HJT was doing the same thing that the cmd promt is doing, closing itself..

im running one of them scanners now, i will let you now if it helps

Open Windows explorer and search for the following files. Let me know if they are present.

C:\Windows\system32\CMD.COM
C:\X.TXT
C:\Z.TXT

You may need to reconfigure Windows XP to show hidden files, folders and extensions. To do this go to Folder Options > View tab and enable "Show hidden files and Folders", be sure to UNCHECK "Hide Protected operating system Files (recommended)" and hit Apply > OK.