When the PC wake's up (boot) and Windows 7 RC starts, I get an error message: "Can not save registration file" What's that and what to do?

That means a "registration file" got lost during the PC's pause (sleep, as you say "wakes up"?). Those files are needed for authentication purposes, as logging-in to websites, identify you to enable customer-specific updates, etc. Does the problem arise on normal shutdowns/restarts or only in "rest/awakening" situations like sleep and hibernate?Mobile AMD64 3000+, VIA Apollo K8T800 chipset, 1 G RAM, ATIRadeonMobility 9700, 20x DVDRW, C:XPSP3 (55G),D:WIN7 (25G),F:DATA (250G)

It occurs not in "wake" from sleep , just when I do full restart e.g. shut down then boot the PC. Windows7 starts, everything looks ok then this message is shown. Everything works fine - currently I simply close this error message window, but I wanted to know what to do in order to fix it.

There is no general answer to this if you can't identify the device or program that uses that registration file. (You could, e.g., force your system to start with a bootlog - "msconfig" setting - and look where this error occurs.) If you don't find anything, you have to wait until someone (a website, a program function, etc.) tells you that you are not entitled to do what you want.Mobile AMD64 3000+, VIA Apollo K8T800 chipset, 1 G RAM, ATIRadeonMobility 9700, 20x DVDRW, C:XPSP3 (55G),D:WIN7 (25G),F:DATA (250G)