Reasons why this is happening:
1: If a channel has been unlinked excessively with different IP's being passed through the YouTube, It will send notifications to the Staff.
2: If you Try to TM (Trade Mark) Claim a YouTube and do it Wrongly YouTube WILL Suspend it without any further Action.
How you can get it unsuspended:
Call up YouTube or send an email to their support team and they can help you out IF You are the rightful owner.