My asp.net pools keeps recycling IIS7 - asp.net

Question

as soon as the box start havif some traffic like 40 to 50 session the poole in my application keeps recycling. So all my shopping cart session are lost. this happens everytime google bot goes thru my site.
Can anyone help
3005
Une exception non gérée s'est produite.
10/07/2011 09:03:03
10/07/2011 09:03:03
6da75f787e534e7dbf738517ec50b169
11641
32
0
/LM/W3SVC/5/ROOT-1-129547308182805050
Full
/
C:\inetpub\voip\
WEB2
3908
w3wp.exe
AUTORITE NT\SERVICE RÉSEAU
NullReferenceException
La référence d'objet n'est pas définie à une instance d'un objet.
http://ttvrip.comCustom.aspx?id=bf932838-304c-4aed-b7d4-b9b3f13bdc05&rcbID=ctl00_MainContentHolder_ContentColumnControl1_ctl01_cboCountry&rcbServerID=cboCountry
/Custom.aspx
66.249.68.162
False
AUTORITE NT\SERVICE RÉSEAU
10
AUTORITE NT\SERVICE RÉSEAU
False
à Telerik.WebControls.RadComboBox.HandleCallBack() dans C:\Documents and Settings\dev\Desktop\rad\ComboBoxSource\ControlLibraryNET20\Code\RadComboBox.cs:ligne 855 à Telerik.WebControls.RadComboBox.OnPreRender(EventArgs e) dans C:\Documents and Settings\dev\Desktop\rad\ComboBoxSource\ControlLibraryNET20\Code\RadComboBox.cs:ligne 990 à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Control.PreRenderRecursiveInternal() à System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Answer 1

There's an error in your code which causes a nullreference exception. This in turns keeps the pool busy. The pool is set to auto-recycle to keep itself alive when an excess of errors occur.
So first off. Fix the error in custom.aspx (it has to do with the combo box for Country perhaps?)
Secondly, save the session for users and their shopping carts in a database. DO NOT RELY on sessions like you're doing now. It'll save you a lot of headaches down the line, plus it has the added benefit of letting you call the data to see abandoned shopping carts and determine which products proved more popular but didn't get checked out and why to improve the overall "click then buy" on your ecommerce site