imported pictures disappear....and their scaling percent becomes: -2

 Hi, I have SWP 5.5 Build 2960, installed on Windows 7 (64 bits). When I take a snapshot of a pdf file then copy it as a picture on SWP, the content of these pictures disappears after a few minutes and always disappears when I reload the SWP document. I noticed that on the properties of the disappeared pictures the horizontal scaling percent becomes -2. This seems to happen for all larger pictures (See for instance the Table 1 in the attached file), not for smaller files.   Thanks!

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pictures disappear scaling -2..tex4.1 KB