Funny you should suggest that about Explorer, because I found the same to be true when I was using LW 2.x on OS 8.5. (I only stopped using that version a month ago!)

Type 1 errors are often related in some way to a problem with RAM. Check to see how much RAM is allocated to LW. Try adding some more if Explorer doesn't solve the issue. Also, I found Java can be an issue, see which version of Java you have installed & see if there's an update around for OS 9.