As today is Sunday, many Candidates must be trying to fill their choices today causing more than usual traffic to the website. And also 10th November is the last date for Choice filling. Might be that also is the reason. Check if your Internet Explorer is 6 and above. Clear the cache, browsing history, passwords, cookies, etc. Also restart your system and relogin. If all this doesn't work, try late in the night or early in the morning when there is less traffic to the website. Also once check if the registered mobile has proper signals and network to receive the OTP.