Hi Erik,
There seems to be another plugin, which is using the same cache library. This issue will be resolved in the next version (1.3), which will be released within the next couple of days.
If you cant wait you have to replace "JG_Cache" with "chimpexpressJG_Cache" in the following files:
[chimpexpress.php at line 198, column 20] $cache = new JG_Cache( $cacheDir );
[chimpexpress.php at line 733, column 16] $cache = new JG_Cache( $cacheDir, $useFTP, $handler );
[class-JG_Cache.php at line 6, column 7] class JG_Cache {
[compose.php at line 409, column 18] $cache = new JG_Cache( $cacheDir, $useFTP, $handler );
Kind regards,
Pete