Homepage crashes every few hours, need to clear cache.

[wind09]

We just did a website redesign and move to a new web server, and this problem keeps happening. The homepage will crash every few house. I keep checking on it, after a while, the page is broken.(only homepage, every other pages are fine.) Sometime it breaks on IE, sometimes on all browsers I use: FF, chrome. I can temporarily fix it by clear system cache. But it keeps coming back, and I don't know what's causing it. Asked the developer, at beginning he thought it might be the css js compressing, but even after he removed that, it still happens. Now he suggested the following reason:
1, apache server misconfiguration
- I contacted the web hosting company, they assured me everything is correctly configured.
2, memory leak
- I'm on a delicate server, besides, why all other pages are fine, but only homepage breaks?
3, jotcache plugin
- I don't know about , how can I find out?

Now comes to the error. This is our website: http://www.fashionmic.com. I'll attach how it looks when it's broken.
When the homepage breaks, I got this js error:
Message: 'jaMegaMenuMoo' is undefined
Line: 183
Char: 4
Code: 0
URI: http://www.fashionmic.com/

I'll also attach the error log when I see this error. Not sure if any of this will cause the page to break.

The developer also said he doesn't know why this is happening. I don't know what I can do now. This is definitely not working if it keeps crashing.

Thanks!

[GlobeOfGeek]

Possibly an error based on the browser you are using. Not all code runs in the same manner on every different web-browser.

Example: An Ajax plugin on my site that ran fine for Google Chrome, crashes horrifically on Iexplore and messes up the front page of the site.

[wind09]

But sometimes it breaks on all browsers. After I clear cache, everything looks fine again. I'm so confused.