Static instance of javascript class is not retained in IE7 on ppr

I have created an application which works with below client-side javascript.

function RtcProvider()
{
this._rtcComponents = new Object();
}

// The static instance that will hold the singleton instance. This should
not be
// acquired directly. It needs to be acquired via the getInstance() method.
RtcProvider.INSTANCE = null;


/**
* Static method to acquire a fully initialized RtcProvider instance.
*/
RtcProvider.getInstance = function()
{
if(RtcProvider.INSTANCE==null)
{
RtcProvider.INSTANCE = new RtcProvider();
}
return RtcProvider.INSTANCE;
}

RtcProvider.prototype.registerComponent = function(component)
{
//add component to this._rtcComponent
}

RtcProvider.prototype.updateData = function(data)
{
//get components from this._rtcComponents and update them
}

The jspx page has some components which when rendered call

"RtcProvider.getInstance().registerComponent() " - 1

method to register themselves on partial/full page refresh. Along with this
the back-end sends a javascript to the page using AJAX. The javascript
content says

"RtcProvider.getInstance().updateData(data)" - 2

The updateData method will update the components registered with the
RtcProvider instance. Since RtcProvider.INSTANCE is a static variable both
these javascript calls should work on the same RtcProvider instance. When the
page is rendered afresh the update happens as expected. However on a partial
page refresh, the static instance of RtcProvider is lost during call 1. This
is seen intermittently in IE7. In short call 1 and call 2 work on separate
RtcProvider instance instead of the same static instance. However this is not
reproducible in IE8 or any other browsers like Firefox, safari etc. Is this a
known issue? Is there a hotfix available for this problem for IE7?