Pc sluggish at start up

For the last few days when i switch on the pc it seems to be sluggish for say 10 minutes.
Normally its fine but i have noticed a difference.
I have run the following but all seems ok.
Spyware blaster.
Malwarebytes Anti-malware.
Disk defragmenter.
Avg.

The light on the front of the pc is flashing away like mad.
Is there something i can try to see what is running at startup that might be the issue.

Thanks.

 

If you are running OneDrive in Win 7 or later it will sync your files at startup and, depending on the volume of new or amended files to be uploaded, this can cause a burst of disk activity. Does that ring any bells?

 

I am using Windows 7 and only have C drive