Got the below error while trying to open the organization.svc in browser. Although rest of the CRM was working properly.
Checked the event log and got this interesting error message over there.
Exception type: InsufficientMemoryException
Exception message: Memory gates checking failed because the free memory (208502784 bytes) is less than 5% of total memory. As a result, the service will not be available for incoming requests. To resolve this, either reduce the load on the machine or adjust the value of minFreeMemoryPercentageToActivateService on the serviceHostingEnvironment config element.
at System.ServiceModel.Activation.ServiceMemoryGates.Check(Int32 minFreeMemoryPercentage, Boolean throwOnLowMemory, UInt64& availableMemoryBytes)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CheckMemoryCloseIdleServices(EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
As suggested by the error message, increasing the RAM resolved the issue.