jQuery Grid Plugin - jqGrid

I have been trying for a number of days to identify the cause or fix this issue I am having withouth any success.  I would really appreciate any help in this matter.

I am using the Struts2-Jquery plugin which uses jqgrid 3.7.2 with Jquery1.4.2.

I get an Unspecified Error Only in IE 8 (works fine in FireFox 3.6.13) when I call

My logic is I have 2 grids, and I can transfer a row from the left grid to the right hand side grid. This all works fine but sometimes I get this Unspecified Error occurring when adding the rowData to the right grid and IE then crashes. In the IE console, I get this Unspecified error at: jquery-1.4.2.js, line 4448 character 5

This error only seems to happen for specific data. This means that I can call addRowData fine in IE for most of my records, but some specific records refuse to be added and this error comes. I still dont know why it happens. I have searched the web but cant find much on this issue. I even tried with jquery 1.4.4.js and the same thing happens.

//Retrieve rowData from left grid

//Delete rowData from left grid

//Add rowData to right grid (problem happens at this line below!) 

Your help is very much appreciated on a solution.

thanks