Symptoms:

After you enter credentials on SharePoint site login prompt, you will be thrown the login prompt repeatedly despite providing the right credentials.

Cause:

This issue occurs with default security settings of IE7 in windows server environment. The settings include a loopback check security feature that is designed to help prevent reflection attacks on your computer. Therefore, authentication fails.

It can also happen for users that are behind a secured network and browser settings are controlled by administrator.

Solution:

To work-around this problem, users need to turn off Integrated Windows Authentication in Internet Explorer.

1. In Internet Explorer, click on the Tools button, then choose Internet Options
2. Click on the advanced tab
3. Clear the Enable Integrated Windows Authentication option (In Security section) and Click “OK”
4. Close and restart Internet Explorer.

If the problem persists, you may need to manually add the team Web site to the list of trusted intranet sites. To do this, complete the following steps:

1. On the Internet Explorer toolbar, click Tools, and then click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then select Local intranet.
3. Click Sites, and then click Advanced.
4. Type the URL of the team Web site in the Add this Web site to the zone box, click Add, and then click OK.

Enable Developer Dashboard via stsadm :

stsadm -o setproperty -pn developer-dashboard -pv ondemand

To disable Developer Dashboard:

stsadm -o setproperty -pn developer-dashboard -pv off

Issue:

If you try to deploy a sandboxed solution and run into this Error

 Cannot start service SPUserCodeV4 on computer

Reason:

Microsoft SharePoint Foundation Sandboxed Code Service is not running on the server.

Solution:

Go to Central Administration -> System Settings -> Manage services on server- > “Microsoft SharePoint Foundation Sandboxed Code Service ”

-> click the “Start” link button to start the service.