I have a grid with a MasterTable and a DetailsTable.
If I expand a row on the MasterTable I can, as you would expact, collapse it again.
If, however, I select a row in the DetailTable and then try and collapse the MasterTable row, I get the following JScript error (in IE8)...
"Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerServerErrorException: Collection was modified; enumeration operation may not execute."
I haven't got any client-side script of my own so it's nothing I've done (at least, not knowingly).
FWIW, the error is reported 62,099 characters in to line 6 of MicrosoftAjax.js.
Anyone any ideas why?