Mathematica version 9.01 works very well an my Windows XP system.

Now, I have updated zu version 10 on a new Windows 7 system, 64bit, same hardware: AMD Athlon(tm) II X2 245 Processor, 2900 MHz, 2 Kern., 4GB RAM

The starting process takes 80 seconds until the welcome screen. In the meantime, I get the message: "Formatting Notebook Contents".

Next, I start a small nb-File, it is open immediately. But, now I can insert only two letters ! Pr instead of PrimeQ[ ]

The systems freezes for about 40 seconds and in the headline appears "No response", no input is possible ...

After the 40 seconds, Mathematica works well for a moment. In the next cell, I can insert only two letters, waiting 40 seconds, and so on.

I have deleted the Directory \ProgramData\Mathematica and Users\Neff\Appdata\Roaming\Mathematica and make a new activation - same result.

Kaspersky's Antivirus tells "no viruses", Malwarebytes says "no malware".

I have installed Mathematica in the directory C:\math_Maa Is ist possible, that this Underscore makes the problem?

Now, what can I do? I'm despaired. Thanks for any answer

Hans