what browser are you using?
try deleting your cookies.
if using firefox:
1. Select "Tools"
2. Select "Options".
3. Select "Privacy".
4. In Private area click "Clear Now".
5. In "Clear Private Data" window put the check mark for "Cookies" and click "Clear Private Data Now".
6. Click OK.
if using IE:
To delete cookies in Internet Explorer 7.0
• Select "Tools"
• Select "Internet Options".
• Open the "General" tab.
• In "Browsing history" area click the "Delete" button.
• In "Delete browsing history" window click "Delete cookies" button and then click "Yes".
• Click Close and then click OK.
To delete cookies in Internet Explorer 6.x
• Select "Tools"
• Select "Internet Options".
• Open the "General" tab.
• Click the "Delete cookies" button.
• Click OK.
check this out: http://www.2privacy.com/www/enable-cookies-disable/delete-cookies.html