Data Execution Prevention or DEP is a mix of hardware and software for windows which checks memory and prevents any code that is viewed as malicious from running on the system. If you are receiving this error when you attempt to run Rohan, this is most likely occurring because windows sees a spike in CCU usage from the launch of Game Guard when the Rohan client is launched. You will have to change the settings of your DEP settings to allow these programs to launch. The following steps were taken from microsoft's website and details can be found here:
Quoted from Microsoft's website:
"If you are logged on as an administrator, you can manually configure DEP to switch between the OptIn and OptOut policies by using the Data Execution Prevention tab in System Properties. The following procedure describes how to manually configure DEP on the computer:
1. Click Start, click Run, type sysdm.cpl, and then click OK.
2. On the Advanced tab, under Performance, click Settings.
3. On the Data Execution Prevention tab, use one of the following procedures:
• Click Turn on DEP for essential Windows programs and services only to select the OptIn policy.
• Click Turn on DEP for all programs and services except those I select to select the OptOut policy, and then click Add to add the programs that you do not want to use the DEP feature.
4. Click OK two times."