I've had a lot of issues back in the day with the codecs. The current version of LSP is working fine for me in 64 Bit mode.
I do believe what causes some of the issues is to have multiple codecs installed on the same machine. I had similar issues last year (not crashing, but really, really slow processing of sequences and writing effects to the grid, and horrendous problems with optimizing taking like 20 mins to complete). I un-installed LSP completely, then deleted all LSP related folders. And re-booted. I then un-installed
ALL codecs, including KLITE and Divx then re-boot.
Then I doubled checked that I had no other codecs installed (there weren't)
Finally I installed LSP, and let it default on the codec install, if you are 64 Bit you need both the 64 bit and 32 bit codecs from KLITE.
If you still have issues with it at 64 Bit, then I'd un-install, delete the LSP folders, re-boot and then install the 32 bit version and only install the 32 bit codecs.
I'm running the latest (version two point eight) of the S/W on a 64 Bit Win7 machine, and I have zero issues with Macros or transitions. The only minor issue I have with the transitions is that the mono transitions (say red middle out transition) do not animate when selecting them on the left hand nav, but it's so minor that I'm not going to fight with the codec gods
