I set PB to create the temporary files in the same folder as the source
Hi, to be more precise the setting you are referring to is to create the temporary EXE in the same folder as the source.
In other words, the temporary target.
There is no promise of temporary files, if any, to be stored there also. So it's not a bug.
With this option turned on, the temporary executable file for running the program from the IDE will be placed inside the source directory. This can be useful if the program depends on files inside the source directory for testing. With this option turned off, the executable is created in the systems temporary directory.
Now : why is this folder used for storing temporary things ? Either the setting for temporary files is not working (a bug ...)
It's the default temporary directory defined by windows, so yes it's probable some of the other tools used in the chain, or even the PB compiler itself, are writing there.
About your problem, you could see if the heuristic level of you antivirus can be lowered, you could set the temp directory in the exclude list of the antivirus (not a very bright idea I admit), or you could make a request in the appropriate forum section to make all the tools used by PB write to a specified temp directory. It could be possible or not, I don't know, considering the assembler and the linker are third party products. You could start to investigate if they can be redirected in using a different temp directory.
I never looked into it, so I don't have idea.
Obviously you could try to contact the antivirus maker and be at his mercy as many people seem so fond to be.
You could be lucky and resolve your problem now and maybe even for the future.