Quartus II Internal Error on finishing fitting

Hi All,

I've posted about internal errors before, but now I am getting a different one. The code was compiling without issue until I changed an "if" condition to use a different register within the module, and now the code won't compile and generates the following error at 92% of the way through fitting. If anyone has any knowledge as to why this might be please let me know. Is re-installing the Quartus II software my only option, or is there something specific my code may be doing that could cause this? (Code snippet is also below)

Thanks for any help!

Variable definition (the first in input from a different module, the second is an output from a FIFO constructed within the module);

input FIFO_Read_Rq;

.

.

.

wire FIRFIFO_Rd_Empty;

Culpable IF statement (the first condition compiles fine, the second - shown here active, does not compile at all;

if(/*FIFO_Read_Rq == 1'b1 && */FIRFIFO_Rd_Empty == 1'b0)

begin

Out_Data[15:0] = PD_Data[15:0];

end

Internal Error Message;

Internal Error: Sub-system: HDB, File: /quartus/h/qtl_object_cache_sys.h, Line: 711

slice->m_locks == 0

Stack Trace:

0x959a0: HDB_ENUM_OPTION::get_value + 0x282a0

0x47e96: HDB_ACTION_PT_INSTANCE::find_design_unit + 0x4f6

0x2117: HDB_FILE_DEPENDENCIES::~HDB_FILE_DEPENDENCIES + 0x1d7

0x1fa3: HDB_FILE_DEPENDENCIES::~HDB_FILE_DEPENDENCIES + 0x63

0x40bb0: HDB_ACTION_PT_INSTANCE::~HDB_ACTION_PT_INSTANCE + 0x250

0x57a5c: HDB_CHIP::reset_visited_flag + 0x33c

0x5db48: HDB_CMP_ACTION_PT_INSTANCE::sweep_timegroups + 0xe8

0x5db6d: HDB_CMP_ACTION_PT_INSTANCE::sweep_timegroups + 0x10d

0x54a87: HDB_CMP_ACTION_PT_INSTANCE::close_pdb_and_clear_cache + 0x127

0x2cbb: HUT_UTIL::restore_cap_inst_from_pdb + 0xfb

0xa736: CSYN_EXPERT:: operator= + 0x89a6

0x45fe4: CSYN_ENV::restore_state + 0x104

0x2751: FSYN_ENV::restore_state + 0x31

0x11acb: CSYN_EXPERT:: operator= + 0xfd3b

0x6a1f: CSYN_EXPERT:: operator= + 0x4c8f

0x4d4b6: CSYN_EXPERT::run_single_algorithm + 0x296

0x4c340: CSYN_EXPERT::run_flow + 0xd0

0x4b891: CSYN_EXPERT::late_fsyn_flow + 0x291

0x48e5a: CSYN_EXPERT::do_physical_synthesis + 0x68a

0x5b888e: VPR_QI_FACADE::vpr_qi_fsyn_fus_init_chle_lib_api + 0xfd41e

0x2c9ad9: VPR_QI_FACADE::~VPR_QI_FACADE + 0xdad19

0x1c5cf9: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x1b05a9

0x1b80fd: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x1a29ad

0x19b275: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x185b25

0x1a2b8d: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x18d43d

0x1c5d5b: VPR_QI_FACADE::vpr_qi_get_start_and_end_progress_bar_perc_for_fsyn + 0x1b060b

0x1db717: VPR_QI_FACADE::vpr_qi_main + 0x27

0x2de91: fitapi_run_vpr + 0x71

0x46e18: FITCC_EXPERT::run_vpr + 0x138

0x48c0f: FITCC_EXPERT:: place_and_route + 0x14f

0x4aff1: FITCC_EXPERT::invoke_fitter + 0x711

0x4798: fcuda_execute + 0x1f8

0xbab9: fmain_start + 0x7f9

0x1525: Legacy_fitter_Init + 0x4b5

0x2618: Legacy_fitter_Init + 0x15a8

0x2168: Legacy_fitter_Init + 0x10f8

0xf8a6: TclInvokeStringCommand + 0xc6

0x112a8: TclEvalObjvInternal + 0x328

0x121b5: TclEvalEx + 0x8d5

0x12d48: TclEvalObjEx + 0x2d8

0x1abbd: Tcl_EvalObjCmd + 0xfd

0x112a8: TclEvalObjvInternal + 0x328

0x56917: TclExecuteByteCode + 0xe47

0xa2376: TclObjInterpProcCore + 0x76

0x112a8: TclEvalObjvInternal + 0x328

0x56917: TclExecuteByteCode + 0xe47

0xa2376: TclObjInterpProcCore + 0x76

0x112a8: TclEvalObjvInternal + 0x328

0x121b5: TclEvalEx + 0x8d5

0x7c117: Tcl_FSEvalFileEx + 0x1d7

0x7a626: Tcl_EvalFile + 0x36

0xc1ff: qexe_ipc_progress_bar_name + 0x12bf

0x11dd6: qexe_get_command_line + 0x1556

0x150d5: qexe_run_tcl_option + 0x585

0x1e03d: qcu_run_tcl_option + 0xb8d

0x156ed: qexe_process_cmdline_arguments + 0x54d

0x15851: qexe_standard_main + 0xa1

0xa7f8: msg_exe_fini + 0x58

0xaf3c: msg_exe_fini + 0x79c

0x1f14: MEM_SEGMENT_INTERNAL::~MEM_SEGMENT_INTERNAL + 0x194

0xb8bf: msg_exe_main + 0x8f

0x1841: BaseThreadInitThunk + 0x19

0x57508: RtlUserThreadStart + 0x20

End-trace

Quartus II 64-Bit Version 13.1.0 Build 162 10/23/2013 SJ Full Version