CRM Custom Ribbon - SelectedControlSelectedItemIds Popup Blocker/Server Error

Hi All,

I have created a custom ribbon button in CRM product entity and calling a webpage as pop-up for updating selected records. the functionality is working fine for records selected below 42, it fails if selected more from Home Grid and Adavce find both.

Below is the code from ribbon customization:

<Url Address="$webresource:PriceAdjustment.html" PassParams="true" WinMode="2" WinParams="height=200, width=400,toolbar=no, menubar=no,location=no">  
<CrmParameter Name="Data" Value="SelectedControlSelectedItemIds" />
</Url>

Scenario1:
when full page (250 records) selected, getting 'A microsoft Dynamics CRM window was unable to Open, and many have been blocked by pop-up blocker.........."

Scenario2: if I selected inbetween, 43-50 records - I get '404 - File or directory not found -The resource you are looking for might have been removed, has its name changed, or is temporarily unavailable'

any ideas?

Thanks
-Sarvesh