ashmaisv.exe is part of the mail provider in Avast
To be me more precise, it is the e-mail protection proxy (POP3/IMAP/SMTP).
So unless you don't want/need it, you need to have it running.
I choose allow and it asks me again after either updating or booting.
If your startup monitor keeps track of changes in files, it is normal that it asks again after a update.
If it always ask after every reboot, check your startup monitor.