I have the exact same problem. Any solution to this. It occurs on my webdatagrid, activation is on and the grid is in batch mode. I insert a row and then try to edit it and like this user clicking on any cell causes the problem. 

After so many time R&D

i have found that if we set the <ig:Activation enable="true">

and clicked on any column( to activate  cell) then do any operation

which is responsible to post back the page below problem come.

Note : keep it  in mind, if page is being  post back first time then only this problem comes.

Can you tell me the reason, why does this problem come?

[FormatException: Input string was not in a correct format.]
   System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +9594283
   System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) +119
   System.String.System.IConvertible.ToInt32(IFormatProvider provider) +46
   System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider) +385
   System.Convert.ChangeType(Object value, Type conversionType) +32
   Infragistics.Web.UI.Framework.Data.DataBot.ChangeType(Object

i am binding the grid on postback also, but when i do edit operation to edit the row

then page postback and error comes

FormatException: Input string was not in a correct format.]
   System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +9594283
   System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) +119
   System.String.System.IConvertible.ToInt32(IFormatProvider provider) +46
   System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider) +385
   System.Convert.ChangeType(Object value, Type conversionType) +32
   Infragistics.Web.UI.Framework.Data.DataBot.ChangeType(Object value, Type toType) +664
   Infragistics.Web.UI.Framework.Data.DataBot.Compare(Object value1, Object value2) +445
   Infragistics.Web.UI.GridControls.GridRecordCollection.FromKey(Object[] dataKey) +227
   Infragistics.Web.UI.GridControls.GridRecordCollection.FromIDPair(IDPair idPair) +77
   Infragistics.Web.UI.GridControls.GridRecordCollection.GetCellFromIDPair(ItemIDPair idPair) +78
   Infragistics.Web.UI.GridControls.Activation.get_ActiveCell() +82
   Infragistics.Web.UI.GridControls.Activation.LoadPositionalProperty(Int32 index, Object value) +170
   Infragistics.Web.UI.Framework.ObjectBase.LoadClientPropsTransactionList(Dictionary`2 list) +368
   Infragistics.Web.UI.GridControls.Activation.LoadClientPropsTransactionList(Dictionary`2 list) +185
   Infragistics.Web.UI.Framework.ObjectBase.LoadTransactionList(Boolean deferLoadPostDataProcessing) +88
   Infragistics.Web.UI.Framework.ObjectBase.Infragistics.Web.UI.IClientState.LoadTransationList(Boolean deferLoadPostDataProcessing) +40
   Infragistics.Web.UI.GridControls.GridBot.LoadClientObjectsTransactionList() +91
   Infragistics.Web.UI.Framework.RunBot.HandleRaisePostDataChangedEvent() +96
   Infragistics.Web.UI.GridControls.GridBot.HandleRaisePostDataChangedEvent() +73
   Infragistics.Web.UI.Framework.Data.FlatDataBoundControl.RaisePostDataChangedEvent() +33
   System.Web.UI.Page.RaiseChangedEvents() +134
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStage

see this post also

http://forums.infragistics.com/forums/t/49450.aspx

If you are binding in the code-behind you should assign the DataSource on PostBack (when paging, sorting, etc.)

My grid has Checkbox template column,

and paging is enable, if i do not bind it on page post back and 

clicked on second page then it give the fallowing javascript Exeception

Actully in my grid only template column is fixed and every thing(columns) creating dynamically.

Object reference not set to an instance of an object
at Infragistic.web.UI.GridControls.WebDataGrid.InstatiateTempaltes()
at Infragistic.web.UI.GridControls.WebDataGrid.BaseGrid.EnsureTemplates()
at Infragistic.web.UI.Framework.Data.FlatDataBoundControl.CreateChldControls()
at Infragistic.web.UI.GridControls.EnsureChildCOntrols()
at System.web.UI.Controls.PreRenderRecursiveInternal()