In case you didn't know, Bieber acted in one of the greatest episodes of "CSI" history -- a cameo that culminated in his character getting shot up in a comically excessive hail of gunfire.

But Helgenberger wasn't his biggest fan -- telling a French radio station shortly after the episode aired ... Bieber "was kind of a brat" on set, locking a producer in a closet and even punching a cake.

Now, Helgenberger appears to have had a change of heart. The other night in L.A., we asked if she'd ever like to work with Bieber again ... and she replied with an enthusiastic "OF COURSE!"