[plt-scheme] Bad, bad, bad 299-407

Hi all,

Today I started a simple script I was asked for and so I got 299-407,
however after a few lines all the code disappeared from definitions
but still the scroll bar was scrollable[1], and mred started to eat
90-99% of my CPU[2]. I closed it perfectly well, and it said nothing.
Fortunately he didn't harm my file! :)

I'll be trying again, hope this doesn't happen again.
Do you know what this might be? Which info should I give you to help with this?

[1] - http://sat.inesc-id.pt/~pocm/archive/407-no-text.png
[2] - http://sat.inesc-id.pt/~pocm/archive/407-eat-cpu.png

Cheers,
--
Paulo Jorge Matos - pocm at sat inesc-id pt
Web: http://sat.inesc-id.pt/~pocm
Computer and Software Engineering
INESC-ID - SAT Group