I have not personally used this method but it appears to
be reasonable and will probably work fine.
Compliments of PC Tech at newbie.org . . .
The mmsystem.dll file controls the XP subsystem that lets
you read old 16Bit DOS programs. This error is caused by
trying to install or run an old program that overwrites
one or both copies of this file.
Usually, one copy is still intact (68kb) and the other one
is larger. You can use the correct copy to replace the bad
one. (This will save having to find another XP system.)
Just follow the instructions below.
Click on Start and choose Run. Type explorer and click OK.
This opens Windows Explorer which basically shows a map of
your drive. In the left window are the folders and the
right window are your files.
Go down the left side and click on the arrow by the
Windows folder. (This will expand it to show the
subfolders under it.)
Find and Click on the 'System' folder then in the right
window locate the 'mmsystem.dll' file. If it's the right
size (68kb), right-click on it and choose copy. If not,
right-click and choose delete.
Go back to the left side and click on the 'system32'
folder. On the right side again find the mmsystem.dll
file. If this is the larger one, right-click and delete if
not, right-click and copy.
Now go back to the left window to whichever folder you
deleted the file from (system or system32), right-click
and choose paste.
If you find that both copies are the wrong size, you can
follow the procedures above to open Windows explorer on
another XP machine and copy the file to disk.
You can also extract the correct file from your XP CD if
needed. You can find instructions on extracting files in
Windows Help.
