This happens when you load a scenario created with the old scenario editor, or load a hacked scenario with special weapons and or characters, wether you created or someone else.
The easiest way to solve this problem is to install the DnC Scenario Pack in solution #3.
Before performing these troubleshooting steps, please check:
1. Do you have a C:/Sierra/SWAT3/Scenarios folder? if not, create one.
2. Did you create a scenario? Did you use the old scenario editor? if so, use newer version of the scenario editor.
3. Did you delete any or all the scenarios from your scenario folder? if so, undo delete and/or bring back all the scenarios you deleted and try again.
4. Did you hack a scenario to add special weapons or characters? if so, replace the scenario with a back up and/or edit the newly hacked weapons/characters to default weapons, such as a AK47 for primary and a Glock_hip for secondary and/or default characters.
Solution 1: You must load the exact problematic scenario in the new scenario editor that can be downloaded at www.swat3reunited.com, and save it again.
Solution 2: If you didn't have a scenarios folder. Create a scenarios folder in your C:/Sierra/SWAT3/ folder and create a scenario using the new scenario editor.
Solution 3: If all else fails .You can download the "DnC Scenarion Pack" and install the scenarios into you scenario folder, (Install means extract the SSE files into your scnarios folder) Be carefull extracting the files because winzip will create a folder in your scenario's folder and this will not work, the scenarios folder should only contain sse files.