Need help! I got blank pages when doing things

-- url of the page with the problem -- : www.maple-crafts.com (now offline)
-- HikaShop version -- : business 2.2.2
-- Joomla version -- : 2.5.10
-- PHP version -- : x.x.x
-- Browser(s) name and version -- : XXXXX x.x.x
-- Error-message(debug-mod must be tuned on) -- : Error_message

Hi, I have a few quite big problem. It concerned with how to communicate with my customer.

PS: I have inserted this statement "<jdoc:include type="message" />" in my template.
PS: I use captcha, named "osolcaptcha". And it works well.

Well, everything looks good on localhost. But...

1) Default Contact Form of Joomla, I got blank page when I tested sending text. Also, there was not
an email appeared in INBOX of email account assigned inside (name@domain) .

2) Registration by Hikashop (index.php?option=com_hikashop&view=user&layout=form&Itemid=...) , I got blank page
when I clicked button to finish this process. I noticed that address of this blank page was not
"index.php?option=com_hikashop&ctrl=checkout&task=activate_page&...". It was and still is when I do the same thing
again on my localhost site. Besides, no email with activation link sent to my email account (hotmail).

However, I found new user created in the backend of joomla and also in hikashop>user. I clicked to activate that new account.
Then I tried to make an order.

3) Of making order, I got blank page when I clicked FINISH button. I should get page with some wording like "Thank you for your purchase"
as it is shown on localhost job. I still got blank page after making a few more order. Also I got no email of those order in my inbox of my name@domain
email.

Well, those just made orders appear in hikashop. Later, I clicked to see list of order and detail of each order. I tried to make changing order status
or quantity of a product. After that I have to send out this change to notify my customer. I still got blank page.

Still, no email of those order was sent to me or my customer email, I guessed.

PS. I got no problem when using hotmail to sending and receiving with my name@domain email
PS. I used to face quite similar problem no. 2 and 3 when I ran my site joomla 1.5.x. with virtuemart.

You know it make thing difficult to my customer and I to communicate each other. I think those problems above have the same issue.
I already asked admin of my hosting service. They told me that they checked and did reset back to default already.

Almost forgot...I noticed that attribute of file permission (see photoA.jpg) is changed automatically without my action. They were writable. when I changed their attribute once, they still were writable. I don't why it happened.

Now I don't know how to solved these problem. Could anyone please recommend and tell how to fix?
Thank you very much in advance.
PKP

My problem is just solved. My hosting admin just inform me.