Well... it's a 138GB partition with approx. 92GB free, so... lot's of free space...

As a matter of fact, it DOES have more than 2 2GB+ .iso files stored on the drive... I am ignorant of the expectation that these files will cause such issues.

Is it entirely unreasonable to expect full defragmentation on a Windows OS drive partition, and why do .iso files cause this behaviour? Please point me to one of the (many, I'm expecting) previous threads dealing with this.

Thanks!