hi, ive bought sig pro this week.
but isnt there an option to show the thumbnails at the bottom of the container wherein the big image is displayed? (sigplus is having such an option).

You could try this:

Go to the sig plugin and change your thumbnail quality to 80. Using an ftp program, set your joomla cache folder permissions to 777. Go into your folder, and find your images. They will have your filename, plus a prefix that is (presumably) generated by SIG. Change the permissions on the images inside the cache folder to 777 and click apply. do this for every image thats not showing up.