I have been looking in to a problem where an Umbraco 4.7.1.1 site with uWebshop goes down multiple times per day at random times.

The application pool stops about 10 times per day at random times and I have not yet found the trigger for it. This problem aside, the site seems to work as usual.

It took me a while to get the debugging info we need, but our hoster enabled crash dumps in order to obtain the stack traces. This is the single exception that causes the application pool to crash every time.

In site-application-pool__PID__17544__Date__08_25_2015__Time_11_05_47AM__351__First chance exception 0XC0000005.dmp the assembly instruction at umbraco.page..ctor(System.Xml.XmlNode)+4ff which does not correspond to any known native Module in the process has caused an access violation exception (0xC0000005) when trying to read from memory location 0x00000000 on thread 49

More stack traces:

System.OverflowException    1    Value was either too large or too small for an Int32.    System.Convert.ToInt32(Double) 
   System.Double.System.IConvertible.ToInt32(System.IFormatProvider) 
   System.Convert.ChangeType(System.Object, System.Type, System.IFormatProvider) 
   System.Xml.Xsl.Runtime.XmlQueryRuntime.ChangeTypeXsltArgument(System.Xml.Xsl.XmlQueryType, System.Object, System.Type) 
   System.Xml.Xsl.Runtime.XmlQueryContext.InvokeXsltLateBoundFunction(System.String, System.String, System.Collections.Generic.IList`1<System.Xml.XPath.XPathItem>[]) 
   System.Xml.Xsl.CompiledQuery.Query.<xsl:template name="compiler:generated">(System.Xml.Xsl.Runtime.XmlQueryRuntime, System.Xml.XPath.XPathNavigator, Double, Double, System.Collections.Generic.IList`1<System.Xml.XPath.XPathNavigator>) 
   System.Xml.Xsl.CompiledQuery.Query.<xsl:template match="/">(System.Xml.Xsl.Runtime.XmlQueryRuntime, System.Xml.XPath.XPathNavigator, Double, Double, System.Collections.Generic.IList`1<System.Xml.XPath.XPathNavigator>) 
   System.Xml.Xsl.CompiledQuery.Query.<xsl:apply-templates>(System.Xml.Xsl.Runtime.XmlQueryRuntime, System.Xml.XPath.XPathNavigator, Double, Double) 
   System.Xml.Xsl.CompiledQuery.Query.Root(System.Xml.Xsl.Runtime.XmlQueryRuntime) 
   System.Xml.Xsl.CompiledQuery.Query.Execute(System.Xml.Xsl.Runtime.XmlQueryRuntime) 
   System.Xml.Xsl.XmlILCommand.Execute(System.Object, System.Xml.XmlResolver, System.Xml.Xsl.XsltArgumentList, System.Xml.Xsl.Runtime.XmlSequenceWriter) 
   System.Xml.Xsl.XmlILCommand.Execute(System.Object, System.Xml.XmlResolver, System.Xml.Xsl.XsltArgumentList, System.Xml.XmlWriter) 
   System.Xml.Xsl.XslCompiledTransform.Transform(System.Xml.XPath.IXPathNavigable, System.Xml.Xsl.XsltArgumentList, System.Xml.XmlWriter, System.Xml.XmlResolver) 
   System.Xml.Xsl.XslCompiledTransform.Transform(System.Xml.XPath.IXPathNavigable, System.Xml.Xsl.XsltArgumentList, System.IO.TextWriter) 
   umbraco.macro.GetXsltTransformResult(System.Xml.XmlDocument, System.Xml.Xsl.XslCompiledTransform, System.Collections.Generic.Dictionary`2<System.String,System.Object>) 
   umbraco.macro.loadMacroXSLT(umbraco.macro, umbraco.cms.businesslogic.macro.MacroModel, System.Collections.Hashtable) 

Anyone an idea where this may come from and how to solve it?