If the problem occurs during CD Analysis, first please deactivate the "detailled CD analysis":
Left click the Virtual CD icon in the SysTray of the task bar -> Settings -> CDs/CD-Drives. Uncheck the option 'Activate the detailled CD the analysis function'. Please also refer to KB #1595.

If this does not solve the problem, another program might access the physical CD-Drive and cause the problem. Very often a change of the Anti-Virus program settings helps.
Please deactivate the Anti-Virus program and try to create a virtual CD.

Further details:

• If you already have created a virtual CD or an ISO-image i.e.e with an elder version of Virtual CD, please try to create a virtual CD using a virtual CD as source.
  This is option is available only if only the 'Permit virtual CD
  drives as source drives' option has been activated on the CDs/CD
  Drives page of the Virtual CD Settings(Left click on Virtual CD icon in the SysTray of the task bar -> Settings -> CDs/CD-Drives).
• Please try to create a virtual CD using the 'Virtual CD Editor'(Left click on Virtual CD icon in the SysTray of the task bar -> CD Management -> File -> Customized virtual CD…).