[CONNECT] BMake Question/Issue

I'm using a VS2013 "make" file project for my app's MDL resources. If I work on an app, then have a few days/weeks break, when I return to that app and run BMAKE again, it fails with "BMAKE: unable to create c:\Temp\5\Bentley\MicroStationSDK\objects\make.opt".

The last time I (successfully) ran BMAKE, it used "c:\temp\3\..." My questions are: 1) why does it sometimes use a different sub-folder, and, 2) Is there any way I can specify a folder to use such that it won't get changed?

Thanks,

Bruce