i got application failure alert in IPS and found that this can be fixed by upgrading IOS. i was using 7.0.4 and tried to upgrade to 7.1.8 latest one. upgrade also failed and error came like analysis engine is busy upgrade failed. then i took backup of config and reimaged the sensor with 7.1.8 E4 and restored the previous config. sensor was booting and hostname is showing as same as previous one but i am not able to login with the previous credentials. any idea ? how to login to the sensor with changing the config ? please help..