WMP10 won`t play content

I sent an MPEG4 video clip to my PC from my camcorder - but when i try to
play the clip on WMP10 i got error message `an audio codec is needed to play
this file..etc` Then redirected to WMPlugins.com to see if missing codec was
available to download.Missing codec was Sharp G.726 audio codec. I downloaded
the codec and tried to play the clip but this time got the error message
`C:Windows/Systems32/AUTOEXEC.NT. The system file is not suitable for running
MS-DOS & Microsoft Windows applications.Choose close to terminate the
application.

Went to microsoft support pages where it tells me that the codec is
supported in WMP for Windows XP (the OS on my PC) but it also states that the
Sharp G.726 codec is no longer "signed"??

After hours wasted i attached the MPEG4 clip to an email and sent to my
brother (whose laptop also has XP as the OS) - who CAN play the clip on
WMP10!!

I am at a loss and need help/advice?

Many thanks in anticipation of yor support,
Regards,
Shaun.

I assume your brother does not have the Sharp G.726 CODEC. But
regardless, it may be beneficial to download GSPOT (free) and use it to
identify the specific attributes of the file, which may then be used
to identify CODECs that may be used to process the file. AND/OR,
download and install FFDSHOW, which has a good chance of being able to
handle your file on its own.