Database in recovery mode

Hi ,

Can some one help me to identify , the reason why the SQL DB is ( user DB) is going to Recovery mode daily in the morning hours in between 7 AM to 11 AM , any time in between . 

I dont have exact clue on the reason behind , but request your help to point out why & the action point to be taken to prevent it.

few points 

1. sql server is an 2008 std 64 Bit

2. have enough disk space on the user DB where their mdf, ldf files are stored.

3. perform full backup daily in the midnight around 12 AM  and perform tlog backups every 30 mins . 

Thanks

hemadri