You can increase the number of GDI objects in win7 in the registry. Open regedit and in “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows\GDIProcessHandleQuota” you can set it. The values allowed there are between 256 and 65536. After changing the value you have to restart. But do not set it to 65k because this is the system wide limit and you do not want to let Nuendo use all GDI objects, or? 
I think a value of 15000-20000 or so, would be fine for you.
Hope this helped.