I don't think that there is any issue with the machine configuration;
Intel® Xeon® Processor E3-1231 v3 (8M Cache, 3.40 GHz)
# of Cores: 4
Processor Base Frequency: 3.4 GHz
Hard Disk: 2TB (RAID 1)
Memory: 32GB
Display: 1280 x 1024 (32-bit)
2. It is happening on clinet machines
3. Since I installaled SAP 9.1
4. Windows automatic updates are set to off to troubleshoot this issue.