pgf is shown as of version 3.0.0 in the package manager, but used in version 2.10

Dear all,

I recently have the problem that some of my .tex files do not compile 
anymore because of version conflicts after I updated my MiKTeX 
distribution. It seems that the package manager shows the pgf package as 
of version 3.0.0, but the logfiles created when compiling my .tex files 
show the line "Package: pgf 2008/01/15 v2.10 (rcs-revision 1.12)". I 
already tried to uninstall and re-install the pgf package using the 
package manager, but that did not solve the problem. How can I fix this?

Best regards,

   Thomas

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