Corrupt .htaccess file?

[chefbyte]

Hi,

Just gave 3 a spin and installed ok as per instructions, tried to sign in and got an internal server error.
I changed the RewriteBase to reflect my sub folder
All folders and files CHMOD as per instructions

.htaccess Existance
/data/ Good 'Deny' file - OK
/data/uploads/ Good 'Allow' file - OK
/data/thumbs/ Good 'Allow' file - OK
/data/pages/ Missing file - Warning
/plugins/ Good 'Deny' file - OK
/data/other/ Missing file - Warning
/data/other/logs/ Missing file - Warning
/theme/ No file - OK

if I rename .htaccess in the root folder, I can log into the site and view all and the health check is all ok?