I have several websites running Umbraco in my own hosting centre.

After a day or two ALL sites stop working in the backend at the same time.

I have set permissions by the book to both c:\windows\temp and all the files in the Umbraco folder.

But nodes are still not showing up!

If I do an IIS Reset it will work fine for about 2 days, then the same problem.

I am running this site on IIS7 on Windows Server 2008.

I get this in the log:

At /umbraco/tree.aspx?rnd=f5fdb9dc-37e3-4bcd-8462-8a2ab5131bb6&id=-1&treeType=content&contextMenu=true&isDialog=false (Referred by: http://www.tidbecks.se/umbraco/TreeInit.aspx?app=content): System.IO.FileNotFoundException: Could not find file 'C:\Windows\TEMP\vydyigvf.dll'.  File name: 'C:\Windows\TEMP\vydyigvf.dll'     at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)     at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy)     at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)     at Microsoft.CSharp.CSharpCodeGenerator.FromFileBatch(CompilerParameters options, String[] fileNames)     at Microsoft.CSharp.CSharpCodeGenerator.FromSourceBatch(CompilerParameters options, String[] sources)     at Microsoft.CSharp.CSharpCodeGenerator.System.CodeDom.Compiler.ICodeCompiler.CompileAssemblyFromSourceBatch(CompilerParameters options, String[] sources)     at System.CodeDom.Compiler.CodeDomProvider.CompileAssemblyFromSource(CompilerParameters options, String[] sources)     at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence)     at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies)     at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)     at System.Xml.Serialization.XmlSerializer.GenerateTempAssembly(XmlMapping xmlMapping, Type type, String defaultNamespace)     at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)     at System.Xml.Serialization.XmlSerializer..ctor(Type type)     at umbraco.BusinessLogic.Utils.SerializableData.Serialize(Object objDeserialized, Type objectType) in d:\TeamCity\buildAgent\work\7380c184e9fcd3ea\umbraco\businesslogic\Utils\SerializableData.cs:line 43     at umbraco.cms.presentation.Trees.XmlTree.ToString() in d:\TeamCity\buildAgent\work\7380c184e9fcd3ea\umbraco\presentation\umbraco\Trees\XmlTree.cs:line 73     at umbraco.cms.presentation.tree.Page_Load(Object sender, EventArgs e) in d:\TeamCity\buildAgent\work\7380c184e9fcd3ea\umbraco\presentation\umbraco\tree.aspx.cs:line 52     at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)     at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)     at System.Web.UI.Control.OnLoad(EventArgs e)     at umbraco.BasePages.BasePage.OnLoad(EventArgs e) in d:\TeamCity\buildAgent\work\7380c184e9fcd3ea\umbraco\businesslogic\BasePages\BasePage.cs:line 287     at System.Web.UI.Control.LoadRecursive()     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)