ServerProtect services will stop and start if the scan engine and virus cleanup engine was updated.

Scan Engine updates will restart the Serverprotect Normal Server service to unload the old scan engine and load the new one into the system's memory. 

Another reason is when there is a Program Upgrade. Program upgrade will also restart the service to load the new files.

To verify, check the Serverprotect logs (ServerProtect Management Console>View Log>View Log) or the server's Application Event log and look for entries similar to below:

Event Type: Information
Event Source: SpntLog
Event Category: Update
Event ID: 4
Date: 12/10/2012
Time: 12:06:35 PM
User: NT AUTHORITY\SYSTEM
Computer: 2003X86-01
Description:
Engine update success: virus scan engine(32 bit) The latest engine version is 9.700-1001