Thank you for your time and patience.
1) Yes, before installing avast i got access to both: files and to run programs.
2) Yes, after i install avast i can't access the "server" (but i can access other data partition on the same fixed disk)
3) I translate the error using google translate, so maybe it sounds different...
"IT DOES NOT HAVE ACCESS TO \\server\C on sever. IT CAN THAT DOES NOT HAVE PERMISSION TO USE THIS RESOURCE OF NETWORK. MAKE CONTACT WITH THE ADMINISTRATOR OF THIS SERVICE TO VERIFY IF IT HAS ACCESS PERMISSIONS.
SPACE OF INSUFFICIENT STORAGE IN THE SERVER TO PROCESS THIS COMMAND.
4) After install avast, i download Ad-Aware and installed on the same PC. But it's the freeware version without real-time protection, just manual scans.
5) I don't have firewall on that PC.
Again, Thank for your help.
Andres