Black and white beach ball ...

I've got a tower circa 2008. When I do a restart I get a black and white spinning beach ball for a few seconds. But it continues to boot without issue. Someone once told me this was a dangerous thing. It's been there for six months or a year. The tower is otherwise working beautifully. In fact I often marvel at its consistency. And I work 8 -10 hours a day for months at a time (editing films).

Is there any way to do a check of the system to see what might be causing the black and white beach ball?

My assumption is that it might be something hardware ... I do my permissions regularly. Disk Warrior doesn't seem to find any problem with the directories.

Just wondering...

Ben