I'm having this issue as well. The docs directory appears to be pointed correctly, and in fact, each time the error pops up, you can watch the file appear in the directory. For example:
Cannot find 'file:///E://BeerSmith2/bsxtmp_10705.htm'. Make sure the path or Internet address is correct.
And then the file bsxtmp_10705.htm appears in the docs directory I specified.