Windows started compressing wav files with IMA ADPCM instead of....

So we have some software the saves audio to wav file format on a windows 7 Pro box.
For years this has been running great and windows has been converting the audio and outputting a wav file with Microsoft PCM format.
Recently something changed.
THe wave files are now IMA ADPCM compression format and it is causing us a lot of trouble.
I have tried to find a way to go back to just PCM but I can't figure it out.

Anyone have any good ideas?

I just want my wav files to always be in Microsoft PCM format.
The software vendor says that this is not their problem and has to do with the codecs on the windows system itself.

Thanks

Thanks for your input fireberd.

More details:

This system runs like a "server"
There is one main piece of software running on it and nothing additionally gets installed or uninstalled.
There is no user for this system.
It sits in a network closet and I am the only administrator that may connect to make slight changes from time to time.
So when it comes to software that has been installed, I have to say there has been nothing, just regular windows updates.
Now granted maybe something was installed in the background or unintentionally but I can't understand what.

Not sure when this problem started, I almost feel like it started out of the blue.

The only software installed recently was:
- Microsoft Silverlight update to version 5.1.4.0.4.16.0
- Microsoft Visual C++ 2008 Redist x64 version 9.0.30729.6161
- Microsoft Security Essentials 4.8.204.0

I just heard back from the software vendor.
Even though they swore that this issue was not on their end and that it had to do with windows now they are saying that the change may have been done by them....

Sorry for bothering everyone.
I guess this wasn't a windows 7 issue afterall.