The first problem looks like a known IE browser bug related to positioned elements and scrollable containers.
Set a CssClass to the containing RadPane and apply a position:relative CSS style to that CSS class.
The second problem could be related to the way you bind RadGrid or possibly - disabled ViewState. Refer to the following resources and provide some more information if you need further assistance.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items