It takes Windows too long to start. Please help

I apologize in advance for my lame English.
I did System Restore, and after 20 minunets or so there was a power outage. When I restarted the pc, it started fast (as usual), when I entered my password, windows started right away (once again, as usual) but there was a message that that System Restore was not completed successfully. Yet, everything seemed to work just fine. Actually, much faster than before. After a while I noticed that Window "Photos" disappeared. So I did "Cancel System Restore". then when I entered my password the screen became dark. windows didn't start. So I shut down the pc and turned it on again. The login screen appeared fast as usual. When I entered my password, once again the screen went dark. After 5 minutes or so, maybe more, windows started. and so far it seems fine. Even "Photos" is back. But I am afraid that next time I restart it won't be.
Please help.
Many thanks in advance