I am having a similar problem, with LM Basic 4.10 on OS10.3.9. The problem actually started about a month ago, before I upgraded from LM 4.9 to 4.10. The program just keeps quitting unexpectedly on me (and that is the error message I get). I now have seven in progress downloads that I can't seem to finish off (as much as 95%!) because everytime I start back up again, I'm always waiting on busy hosts. Shortly after it finally does start downloading something, it quits! I seem to be uploading quite fine (with the exception that it quits), but I can't seem to download anymore. I have 10Gigs free on my HD, and 512mb ram. I've even closed all other programs, but it doesn't seem to help the problem. If I don't find a solution soon, I am going to give up entirely on the whole thing because clearly I have more important things to do with my day.