System hangs up after waking up from sleep mode

 Hi,

I am running Vaio VPCZ12s9r/s  Windows 7 x64 factory installed. All of a sudden the system started to hang up each time I wake PC up from stand-by mode. The mouse changes to the hourglass mouse, but no other changes occur visually.  I try Ctrl-Alt-Del, but nothing appears. The only way to recover the computer is to perform the power-button hard-restart. 

Reading the therad https://answers.microsoft.com/en-us/windows/forum/all/system-hangs-up-after-waking-up-from-sleep-mode/9dfd8202-302e-42e4-af47-ec986c3a5b05?auth=1 I got to go to BIOS and see what sleep mode is used: S1 or S3, but I cannot as I do not  have an advanced BIOS access on the machine as the access restricted.

Could anyone help?

Thanks.