Conditional Drop Down Lists

Hi,

I am using excel 2007 and have come across an issue.

I have to columns. The first is called "Task" and the 2nd is called "Task Description". Both of these columns are currently drop down lists. Task Description drop down list is changed depending on the selection chosen from the "Task" cell. I am doing this by using data validation and setting the conditional list to be "=INDIRECT(Task)" and then the task has a pre-stored list of possible task descriptions.

The issue I have is that only 2 of the possible 6 choices from the task have a set list for descriptions and the others are meant to be filled in manually. However since I used data validation it requires it to be from the list. Is there any way to have only certain values for "Task" have a list and the others be manually entered.

Thanks in Advance