I'm also getting this error in IE8. However, I'm not using formedit at all, just loading grid.formedit.js. Perhaps there's an problem where if you load grid.formedit.js and never use it, it breaks something?
I'm getting the same behavior, but only when the resulting data has 0 rows. Check and make sure that the data your server is returning has more than 0 rows. I already filed a bug about the “0 rows causes Grid to hang on Loading…”
I was wondering what the maintainer's position on this was. I would like this behavior as well in jqGrid. Hopefully, it could use jQuery's selectable module instead of using its own custom implementation.
