Windows 7: Windows Security Prompt for credentials Intermittent on Win7 not Xp

I am seeing an issue on Windows 7, that does not appear in Windows XP. Please let me know if you have seen this or addressed one like it.

Java application is running on web server with Apache and tomcat, on windows server 2008r2. As a user I log into the application every day with windows xp client and access it okay no issues.



If I access same application on windows 7 machine, every once in awhile I will receive a Windows Security prompt with the name of the machine, asking for username and password. It is basic Windows Security prompt. If I work in application it may happen once an hour or more, but I am able to access application okay. I am using a direct logon to my application with no single sign on solution.

I am wondering why might I be receiving this prompt? As I mentioned, it doesn't give me the prompt when using xp client. Has anyone received this or know why the prompt might be coming up?