Thanks for the suggestion but It hasn't helped :(

The only thing I have trouble with is inserting the attachment to the database:

Database.Saveresult sr = Database.insert(attach);

If I comment out that line I dont have any problems but otherwise I get

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Here is my Controller:

public with sharing class clsWebToCase {
    public Blob file {get; set;}
    public Case newCase {get; set;}
    public String fileName {get;set;}
    public String contentType {get; set;}
    public Boolean submitted {get;set;}
    
    public clsWebToCase(){
    	submitted=false;
    	newCase = new Case();
    }
    
    //create case and upload attachment, if any exists
    public PageReference CreateCase(){
    	Database.Saveresult sr;
    	
    	newCase.AccountId = newCase.Contact.AccountId;
    	newCase.Status = 'New';
    	newCase.RecordTypeId = [SELECT Id FROM RecordType WHERE Name='Application Project' AND SobjectType='Case' LIMIT 1].Id;
    	newCase.SuppliedEmail = newCase.Contact.Email;
    	newCase.SuppliedPhone = newCase.Contact.Phone;
    	newCase.OwnerId = '00G20000001QJeE'; //Application Projects Queue
    	sr = Database.insert(newCase);
    	if(fileName != null && fileName != ''){
    		Attachment attach = new Attachment();
    		attach.Body = file;
    		attach.Name = fileName;
    		attach.ContentType = contentType;
    		attach.parentId = newCase.id;
    		sr = Database.insert(attach);
    	}
    	ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.INFO, 'Your case has been submitted - Thank You'));
    	submitted = true;
		return null;
    }
}

and here is the insert section of the page:

    <apex:pageBlock mode="edit" title="Choose file to attach" id="AttachFile" rendered="{!OR(NOT(submitted),(fileName != null))}">
        <apex:pageblockSection title="Attachment"  collapsible="false">
            <apex:inputFile value="{!file}" filename="{!fileName}" contentType="{!contentType}" rendered="{!NOT(submitted)}"/>
            <apex:outputText value="{!fileName}" rendered="{!submitted}"/>
        </apex:pageblockSection>
    </apex:pageBlock>

Anyone have any Ideas why I get this error?

Thanks

Steven