Follow this steps to access SYS and PRIVATE folders of memory card without using a pc:
-Open default file manager
-press options-find, and choose memory card
-write the name of that folder you want to browse (either sys or private), press "find", and wait.
-the folder will appear in search results.Now just select it and begin browsing

You can use it, for example, to delete those themes that don't appear in "App. Manager".Themes are located at E:\private\10207114\import\

If you have problems, i.e. a folder doesn't appear in search results, put you memory card in a card reader, and clear "hidden" attribute of that folder that's not appearing."File manager" doesn't show hidden folders.

Warning:
If you use "File manager" to create a folder anywhere, it may set "hidden" attribute to "private" folder, and it will not appear anymore

For more details, visit Alberto Bilheteria's official web site: br.geocities.com/abilheteria/bilheteria.htm

Thanx for this vital info, I have search in my Memory card for sys folder and it appeared!! :) but I found there is an Uninstall folder with alot of sub-folders containing XXX.log?? is it safe to delete them are those leftovers?? if yes let me know and thank you!

You're still not getting anything like fill access. There is no way to access the data caged directories. Some third party file managers already allow this level of access.