Cannot Install software in Win XP

[vinitparekh]

I have WinXP Professional. Whenever i try to install some software it says "Win16 Subsystem was unable to enter Protected mode, DOSX.EXE must be in your AUTOEXEC.NT and present in your PATH".
I checked the AUTOEXEC.NT and it has DOSX.EXE in it's PATH but when i ran DOSX.EXE the DOS came up and it said

Cannot run this 16-bit protected mode application;
The DOS extender has encountered an error initializing the extended memory manager.

Somebody please help me....

[lost-and-found]

is it happening with some older application that you are trying to install? or is it with any program you install?

Here's my take on it: since win xp is built on the NT core and is not running as a DOS shell, it is known to have problems running older apps, especially apps with DOS requirements. Some apps just won't run.