I log to my site and when i click on categories it come up with this

"The requested URL /b2b/soho was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

Any idea how to fix it before i reinstall the program again
Thank you

I try to do a clean install 1.1.9
and it stop the installation with this error
Sorry, but error occurred during installation:
OK:
Fatal error: Call to a member function write() on a non-object in /home/......../public_html/b2b/core/lib/cache.php on line 53

9101::App Warning
Info
Extension slideshow2 overrides core template with blocks/slideshow2.tpl in /home/*******/public_html/shop/core/engine/view.php on line 279

Everytime to go to my shopfront this is visible at the bottom of the page
how i can stop this
i am usi ng version 1.1.8 with html5 template

9101::App Warning
Extension banner_manager overrides core template with pages/extension/banner_manager_form.tpl in /home/greciaco/public_html/shop/core/engine/view.php on line 279

Every time i m on storefront at the bottom there is this error
how i can fix this

this error it coming up everytime i try to acces my product


"Not Found

The requested URL /b2b/stanford-st12r was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

I need to use by a meter in the item but at the check point it calculate only the first number not the decimal 
e.g.
sell by 1.5 meter x $20.00 = $30.00 
check out 1 x $20.00 =$20.00