SQL Server Disconnecting users after a minor problem

Welcome,

I'm writing because im puzzled by some problem.  In on of our company's facilite there is a Windows Server 2012 with SQL Server 2008 R2 installed. On 25/08/2014 there was error of allocating space because a disk was full. After administrator saw that he deleted unnecessary files and it seemed that problem went away. However later users using out application reported being disconnected from SQL Server at random timings and usually after they left computer and came back. The same day the problems started there were executed scripts. Mostly selects, actual execution plans for them and ones below

	EXEC sp_configure
	'show advanced option',
	'1' ;
	RECONFIGURE ;
	EXEC sp_configure
	EXEC sp_configure
	'show advanced option',
	'0' ;
	RECONFIGURE ;

SELECT 
	ddips.avg_fragmentation_in_percent,
		ddips.fragment_count,
		ddips.page_count,
		ddips.avg_page_space_used_in_percent,
		ddips.record_count,
		ddips.avg_record_size_in_bytes
	FROM 
		 sys.dm_db_index_physical_stats(DB_ID('db'),
		OBJECT_ID(N'tab_name'),NULL, NULL,
		'Sampled') AS ddips

DBCC SHOW_STATISTICS... -- For various tables and indexes

Administrator reports that restarting the whole server helps the situation for about a day and then everything gets back to that errors again.

Some of the errors and warning from Logs:

Volume Shadow Copy Service error: Unexpected error calling routine RegOpenKeyExW(-2147483646<c/>SYSTEM\CurrentControlSet\Services\VSS\Diag<c/>...).  hr = 0x80070005<c/> Access is denied.<nl/>.<nl/>

Windows Management Instrumentation has stopped WMIPRVSE.EXE because a quota reached a warning value. Quota: HandleCount  Value: 4099 Maximum value: 4096 WMIPRVSE PID: 13452 Providers hosted in this process: %systemroot%\system32\wbem\cimwin32.dll<c/> %systemroot%\system32\wbem\mgmtprovider.dll


This directory partition has not been backed up since at least the following number of days.<nl/><nl/><nl/><nl/>Directory partition:<nl/><nl/>DC=ForestDnsZones<c/>DC=NTLU11<c/>DC=local<nl/><nl/><nl/><nl/>'Backup latency interval' (days):<nl/><nl/>90<nl/><nl/><nl/><nl/>It is recommended that you take a backup as often as possible to recover from accidental<nl/>loss of data. However if you haven't taken a backup since at least the 'backup latency interval'<nl/>number of days<c/> this message will be logged every day until a backup is taken. You can take<nl/>a backup of any replica that holds this partition.<nl/><nl/><nl/><nl/>By default the 'Backup latency interval' is set to half the 'Tombstone Lifetime Interval'. If<nl/>you want to change the default 'Backup latency interval'<c/> you could do so by adding the<nl/>following registry key.<nl/><nl/><nl/><nl/>'Backup latency interval' (days) registry key:<nl/><nl/>System\CurrentControlSet\Services\NTDS\Parameters\Backup Latency Threshold (days)


This computer has at least one dynamically assigned IPv6 address.For reliable DHCPv6 server operation<c/> you should use only static IPv6 addresses.


The DNS server is waiting for Active Directory Domain Services (AD DS) to signal that the initial synchronization of the directory has been completed. The DNS server service cannot start until the initial synchronization is complete because critical DNS data might not yet be replicated onto this domain controller. If events in the AD DS event log indicate that there is a problem with DNS name resolution<c/> consider adding the IP address of another DNS server for this domain to the DNS server list in the Internet Protocol properties of this computer. This event will be logged every two minutes until AD DS has signaled that the initial synchronization has successfully completed.


Microsoft SSIS Service: <nl/>Registry setting specifying configuration file does not exist. <nl/>Attempting to load default config file.

Name resolution for the name _ldap._tcp.dc._msdcs.NTLU11.local. timed out after none of the configured DNS servers responded.


Windows detected your registry file is still in use by other applications or services. The file will be unloaded now. The applications or services that hold your registry file may not function properly afterwards.  <nl/><nl/> DETAIL - <nl/> 6 user registry handles leaked from \Registry\User\S-1-5-21-3862299844-3999608137-1596193916-500:

Can you aim me where the problem may lie because i can't think of anything. Also there is a Symantec antivirus installed but it has been installed for a long time and there was no such a problem like now.