Search Keyword error on changing the number of products to be loaded per page

[maverick24]

Hi all,

I am having some problems on the block search function with v1.4.3. Previously upgraded from v1.3.1 to v1.4.3.
After doing a successful search with the keyword and the products are correctly listed.
When I wish to change the number of products to be loaded per page from 10 to 20, it results in a "Please type a search keyword" error.

Can anyone help to advise on which file's coding I can modify to attain the following url?

hxxp://localhost/search?n=20&submit_search=Search&orderby=price&orderway=asc
to
hxxp://localhost/search?search_query=tops&n=20&submit_search=Search&orderby=price&orderway=asc


Thanks in advance.