Losing back-button history in Opera 10.6

[Rick]

I've done a google search for this problem but I found nothing. I'm hoping 
this list can help.

I updated Opera from 10.10 to 10.60 and then 10.61 using the Update Manager.  
Both 10.6 versions had the same problem: after visiting a few web pages, the 
back button loses its history. In other words, if I use the back button to go 
back to an earlier page, I can't. The back button has forgotten the pages that 
I visited earlier. I can still access these pages by bringing up the history 
panel, but the back button has completely forgotten them.

Has anyone else experienced this problem? Can it be fixed?

Thanks!