Hacking R4 III Upgrade help

[Nebz]

I managed to download the Jet Set Radio Future theme off of Filetrip and it turned out to look very well on my R4. My problem is that when I use just about any other theme and go to look at my games the bottom screen turns half fuzzy (sort of like static from an old television). T
hough it's not a huge issue, I was just wondering if this may be normal when using themes or if there actually may be a fix to this?