This is a problem that the guys who are developing Wagic (link) are currently having. It is something that doesnt happen all the time but is a nagging issue and sometimes will happen all the time. Its rendering dual screens that are all purple. Its not supposed to do either.
Heres the log on the SVN: Issue 92 - wagic - PSP: Screen purple & divided in 2 at startup - Project Hosting on Google Code
This issue was also found by another dev awhile ago but no solution apparently found that works, at least not here: forums.ps2dev.org :: View topic - Weird screen behavior
Any help with this issue would be fantastic.