Can't run DOS (command.com)

[FireDragon]

Wonder if anybody knows what's going on.... I've always used DOS no problem on computer. However, I now get the message below when I try to run command.com.

C:\WINDOWS\System32\command.com
C:\WINDOWS\SYSTEM32\AUTOEXEC.NT. The system file is not suitble for running MS-DOS and Microsoft Windows applications. Chose 'Close' terminate the appliction.

If I choose the 'ignore' option, (which comes up in the box, alongside the 'Close' option, the application terminates also.

The only thing different I've done recently is to download AVG, to kill off some viruses. (had 27 infected items).

I can't understand why I suddenly can't use DOS anymore. Please can anyone help?

NB Running Windows XP, home user.

[spannersatcx]

ms knowledge base answer (http://support.microsoft.com/default.aspx?scid=kb;en-us;324767)

[FireDragon]

Thanks for that

[G7SWZ]

The answer in the MS Knowledge base often only works until you reboot the system and then the problem returns.

This is because SP2 actually deletes the file autoexec.nt each time it closes down.

The MS help line suggests reinstalling XP and SP2 but in my experience that did not work.

A work around to solve the problem is to right click on the file autoexec.nt to select properties and to check the box to make the file read only.

Since I made that change I have had no further problems