Hi,

 I am having issues with this 'AdvancedLogin/ImageChallenge.captcha.aspx' which is causing my DNN instance to error. I am not sure what to think of this as it does not seem to be a failed captcha input since I have tested that scenario but whatever it is it eventually leads to a memory run-up on our server and an subsequent reset of the app pool
Here is the error

RawURL: /DesktopModules/AdvancedLogin/ImageChallenge.captcha.aspx
AbsoluteURL: /DesktopModules/AdvancedLogin/ImageChallenge.captcha.aspx
AbsoluteURLReferrer: 
UserAgent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; GTB6.6; FunWebProducts; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.2; Tablet PC 2.0; OfficeLiveConnector.1.5; OfficeLivePatch.1.3; .NET4.0C; .NET4.0E)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: acd275f8-c086-453c-a2d8-87ee0bef1ded
InnerException: Input string was not in a correct format.
FileName: 
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Number.StringToNumber
StackTrace: 
Message: System.FormatException: Input string was not in a correct format. at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) at DotNetNuke.UI.WebControls.CaptchaControl.GenerateImage(String encryptedText)
Source: 
Server Name: WIN-NFKVLU6QK4G

We have since also implemented some Google recaptcha as an option.