i get ya.. i load my tapes that way all the time, however the only time i experience this is when im rushing to switch tapes.. usually (in my case anyway) its user error which causes this phenomenon. the tape MUST be pushed in slowly and evenly all the way till it no longer budges.

oh well...

I've had the same experience as Bogdan just this past weekend. But I'm inclined not to think it due to dirt or misalignment, but possibly to heat, at least in my case. The cam got pretty hot, as I had it in quick start mode for at least six hours and shot almost three hours worth of tape in that period. The mosaic or venetian blinds (I like the descriptiveness of the latter term) seemed to occur once in each of the three tapes I shot, and for just a second or two. Could be the tape, but I'm using Frank's favorite brand and only that brand, so... (also, I always load my tapes vertically - easy to do with a top loading cam). I should add that I was in night view mode most of the time, so this possibly added to the heat issue.

I also experienced so far ONCE, with my TDK tape.

Se we can rule out, its not because of mis alignment, or head clog or lubrication problem . It could be the default behavior, it happened only when i suddenly pressed the play button when i want to watch on TV.
May be the tape running motor and dv reading mechanism synchronization, takes little bit time to adjust with.

WE CANNOT SAY THIS IS DROP OUT OR TAPE MIXING OR LUBRICATION OR MISALIGNMENT or any tape problem. All tapes have the same behavior.

When i play the next time same clip, no problem, just to rule out dropout.

It doesnt matter what tape we use, just stick with one, GOLDEN RULE.. lol.